diff --git a/services/surfaceflinger/Tracing/TransactionDataSource.cpp b/services/surfaceflinger/Tracing/TransactionDataSource.cpp
new file mode 100644
index 0000000..05b89b8
--- /dev/null
+++ b/services/surfaceflinger/Tracing/TransactionDataSource.cpp
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "TransactionDataSource.h"
+#include "TransactionTracing.h"
+
+#undef LOG_TAG
+#define LOG_TAG "TransactionTracing"
+
+#include <log/log.h>
+
+namespace android {
+
+void TransactionDataSource::Initialize(TransactionTracing& transactionTracing) {
+    mTransactionTracing.store(&transactionTracing);
+
+    auto args = perfetto::TracingInitArgs{};
+    args.backends = perfetto::kSystemBackend;
+    perfetto::Tracing::Initialize(args);
+
+    perfetto::DataSourceDescriptor descriptor;
+    descriptor.set_name(kName);
+    TransactionDataSource::Register(descriptor);
+}
+
+void TransactionDataSource::UnregisterTransactionTracing() {
+    mTransactionTracing.store(nullptr);
+}
+
+void TransactionDataSource::OnSetup(const TransactionDataSource::SetupArgs& args) {
+    const auto configRaw = args.config->surfaceflinger_transactions_config_raw();
+    const auto config =
+            perfetto::protos::pbzero::SurfaceFlingerTransactionsConfig::Decoder{configRaw};
+
+    if (config.has_mode() && config.mode() != TransactionTracing::Mode::MODE_UNSPECIFIED) {
+        mMode = static_cast<TransactionTracing::Mode>(config.mode());
+    } else {
+        mMode = TransactionTracing::Mode::MODE_CONTINUOUS;
+        ALOGV("Received config with unspecified 'mode'. Using 'CONTINUOUS' as default");
+    }
+}
+
+void TransactionDataSource::OnStart(const StartArgs&) {
+    ALOGV("Received OnStart event");
+    if (auto* p = mTransactionTracing.load()) {
+        p->onStart(mMode);
+    }
+}
+
+void TransactionDataSource::OnFlush(const FlushArgs&) {
+    ALOGV("Received OnFlush event");
+    if (auto* p = mTransactionTracing.load()) {
+        p->onFlush(mMode);
+    }
+}
+
+void TransactionDataSource::OnStop(const StopArgs&) {
+    ALOGV("Received OnStop event");
+}
+
+TransactionTracing::Mode TransactionDataSource::GetMode() const {
+    return mMode;
+}
+
+std::atomic<TransactionTracing*> TransactionDataSource::mTransactionTracing = nullptr;
+
+} // namespace android
+
+PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS(android::TransactionDataSource);
diff --git a/services/surfaceflinger/Tracing/TransactionDataSource.h b/services/surfaceflinger/Tracing/TransactionDataSource.h
new file mode 100644
index 0000000..be8373b
--- /dev/null
+++ b/services/surfaceflinger/Tracing/TransactionDataSource.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "TransactionTracing.h"
+
+#include <perfetto/tracing.h>
+
+namespace android {
+
+/*
+ * Thread local storage used for fast (lock free) read of data source's properties.
+ *
+ */
+struct TransactionDataSourceTlsState {
+    template <typename TraceContext>
+    explicit TransactionDataSourceTlsState(const TraceContext& trace_context) {
+        auto dataSource = trace_context.GetDataSourceLocked();
+        mMode = dataSource.valid() ? dataSource->GetMode()
+                                   : TransactionTracing::Mode::MODE_CONTINUOUS;
+    }
+
+    TransactionTracing::Mode mMode;
+};
+
+struct TransactionDataSourceTraits : public perfetto::DefaultDataSourceTraits {
+    using TlsStateType = TransactionDataSourceTlsState;
+};
+
+/*
+ * Defines the Perfetto custom data source 'android.surfaceflinger.transactions'.
+ *
+ * Registers the data source with Perfetto, listens to Perfetto events (setup/start/flush/stop)
+ * and writes trace packets to Perfetto.
+ *
+ */
+class TransactionDataSource
+      : public perfetto::DataSource<TransactionDataSource, TransactionDataSourceTraits> {
+public:
+    static void Initialize(TransactionTracing&);
+    static void UnregisterTransactionTracing();
+    void OnSetup(const SetupArgs&) override;
+    void OnStart(const StartArgs&) override;
+    void OnFlush(const FlushArgs&) override;
+    void OnStop(const StopArgs&) override;
+    TransactionTracing::Mode GetMode() const;
+
+    static constexpr auto* kName = "android.surfaceflinger.transactions";
+    static constexpr perfetto::BufferExhaustedPolicy kBufferExhaustedPolicy =
+            perfetto::BufferExhaustedPolicy::kStall;
+    static constexpr bool kRequiresCallbacksUnderLock = false;
+
+private:
+    static std::atomic<TransactionTracing*> mTransactionTracing;
+    TransactionTracing::Mode mMode;
+};
+
+} // namespace android
+
+PERFETTO_DECLARE_DATA_SOURCE_STATIC_MEMBERS(android::TransactionDataSource);
diff --git a/services/surfaceflinger/Tracing/TransactionRingBuffer.h b/services/surfaceflinger/Tracing/TransactionRingBuffer.h
index e6f85ca..7d1d3fd 100644
--- a/services/surfaceflinger/Tracing/TransactionRingBuffer.h
+++ b/services/surfaceflinger/Tracing/TransactionRingBuffer.h
@@ -47,7 +47,7 @@
         mUsedInBytes = 0U;
     }
 
-    void writeToProto(FileProto& fileProto) {
+    void writeToProto(FileProto& fileProto) const {
         fileProto.mutable_entry()->Reserve(static_cast<int>(mStorage.size()) +
                                            fileProto.entry().size());
         for (const std::string& entry : mStorage) {
@@ -56,24 +56,6 @@
         }
     }
 
-    status_t writeToFile(FileProto& fileProto, std::string filename) {
-        ATRACE_CALL();
-        writeToProto(fileProto);
-        std::string output;
-        if (!fileProto.SerializeToString(&output)) {
-            ALOGE("Could not serialize proto.");
-            return UNKNOWN_ERROR;
-        }
-
-        // -rw-r--r--
-        const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
-        if (!android::base::WriteStringToFile(output, filename, mode, getuid(), getgid(), true)) {
-            ALOGE("Could not save the proto file %s", filename.c_str());
-            return PERMISSION_DENIED;
-        }
-        return NO_ERROR;
-    }
-
     status_t appendToStream(FileProto& fileProto, std::ofstream& out) {
         ATRACE_CALL();
         writeToProto(fileProto);
diff --git a/services/surfaceflinger/Tracing/TransactionTracing.cpp b/services/surfaceflinger/Tracing/TransactionTracing.cpp
index 8aacbca..0517984 100644
--- a/services/surfaceflinger/Tracing/TransactionTracing.cpp
+++ b/services/surfaceflinger/Tracing/TransactionTracing.cpp
@@ -25,6 +25,7 @@
 
 #include "Client.h"
 #include "FrontEnd/LayerCreationArgs.h"
+#include "TransactionDataSource.h"
 #include "TransactionTracing.h"
 
 namespace android {
@@ -34,15 +35,20 @@
       : mProtoParser(std::make_unique<TransactionProtoParser::FlingerDataMapper>()) {
     std::scoped_lock lock(mTraceLock);
 
-    mBuffer.setSize(mBufferSizeInBytes);
+    mBuffer.setSize(CONTINUOUS_TRACING_BUFFER_SIZE);
+
     mStartingTimestamp = systemTime();
+
     {
         std::scoped_lock lock(mMainThreadLock);
         mThread = std::thread(&TransactionTracing::loop, this);
     }
+
+    TransactionDataSource::Initialize(*this);
 }
 
 TransactionTracing::~TransactionTracing() {
+    TransactionDataSource::UnregisterTransactionTracing();
     std::thread thread;
     {
         std::scoped_lock lock(mMainThreadLock);
@@ -53,21 +59,94 @@
     if (thread.joinable()) {
         thread.join();
     }
+}
 
-    writeToFile();
+void TransactionTracing::onStart(TransactionTracing::Mode mode) {
+    // In "active" mode write the ring buffer (starting state + following sequence of transactions)
+    // to perfetto when tracing starts (only once).
+    if (mode != Mode::MODE_ACTIVE) {
+        return;
+    }
+
+    writeRingBufferToPerfetto(TransactionTracing::Mode::MODE_ACTIVE);
+
+    ALOGV("Started active mode tracing (wrote initial transactions ring buffer to perfetto)");
+}
+
+void TransactionTracing::onFlush(TransactionTracing::Mode mode) {
+    // In "continuous" mode write the ring buffer (starting state + following sequence of
+    // transactions) to perfetto when a "flush" event is received (bugreport is taken or tracing is
+    // stopped).
+    if (mode != Mode::MODE_CONTINUOUS) {
+        return;
+    }
+
+    writeRingBufferToPerfetto(TransactionTracing::Mode::MODE_CONTINUOUS);
+
+    ALOGV("Flushed continuous mode tracing (wrote transactions ring buffer to perfetto");
+}
+
+void TransactionTracing::writeRingBufferToPerfetto(TransactionTracing::Mode mode) {
+    // Write the ring buffer (starting state + following sequence of transactions) to perfetto
+    // tracing sessions with the specified mode.
+    const auto fileProto = writeToProto();
+
+    TransactionDataSource::Trace([&](TransactionDataSource::TraceContext context) {
+        // Write packets only to tracing sessions with specified mode
+        if (context.GetCustomTlsState()->mMode != mode) {
+            return;
+        }
+        for (const auto& entryProto : fileProto.entry()) {
+            const auto entryBytes = entryProto.SerializeAsString();
+
+            auto packet = context.NewTracePacket();
+            packet->set_timestamp(static_cast<uint64_t>(entryProto.elapsed_realtime_nanos()));
+            packet->set_timestamp_clock_id(perfetto::protos::pbzero::BUILTIN_CLOCK_MONOTONIC);
+
+            auto* transactionsProto = packet->set_surfaceflinger_transactions();
+            transactionsProto->AppendRawProtoBytes(entryBytes.data(), entryBytes.size());
+        }
+        {
+            // TODO (b/162206162): remove empty packet when perfetto bug is fixed.
+            //  It is currently needed in order not to lose the last trace entry.
+            context.NewTracePacket();
+        }
+    });
 }
 
 status_t TransactionTracing::writeToFile(const std::string& filename) {
-    std::scoped_lock lock(mTraceLock);
+    auto fileProto = writeToProto();
+
+    std::string output;
+    if (!fileProto.SerializeToString(&output)) {
+        ALOGE("Could not serialize proto.");
+        return UNKNOWN_ERROR;
+    }
+
+    // -rw-r--r--
+    const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
+    if (!android::base::WriteStringToFile(output, filename, mode, getuid(), getgid(), true)) {
+        ALOGE("Could not save the proto file %s", filename.c_str());
+        return PERMISSION_DENIED;
+    }
+
+    return NO_ERROR;
+}
+
+perfetto::protos::TransactionTraceFile TransactionTracing::writeToProto() {
+    std::scoped_lock<std::mutex> lock(mTraceLock);
     perfetto::protos::TransactionTraceFile fileProto = createTraceFileProto();
-    addStartingStateToProtoLocked(fileProto);
-    return mBuffer.writeToFile(fileProto, filename);
+    const auto startingStateProto = createStartingStateProtoLocked();
+    if (startingStateProto) {
+        *fileProto.add_entry() = std::move(*startingStateProto);
+    }
+    mBuffer.writeToProto(fileProto);
+    return fileProto;
 }
 
 void TransactionTracing::setBufferSize(size_t bufferSizeInBytes) {
     std::scoped_lock lock(mTraceLock);
-    mBufferSizeInBytes = bufferSizeInBytes;
-    mBuffer.setSize(mBufferSizeInBytes);
+    mBuffer.setSize(bufferSizeInBytes);
 }
 
 perfetto::protos::TransactionTraceFile TransactionTracing::createTraceFileProto() const {
@@ -75,8 +154,8 @@
     proto.set_magic_number(
             uint64_t(perfetto::protos::TransactionTraceFile_MagicNumber_MAGIC_NUMBER_H) << 32 |
             perfetto::protos::TransactionTraceFile_MagicNumber_MAGIC_NUMBER_L);
-    auto timeOffsetNs = static_cast<std::uint64_t>(systemTime(SYSTEM_TIME_REALTIME) -
-                                                   systemTime(SYSTEM_TIME_MONOTONIC));
+    auto timeOffsetNs = static_cast<uint64_t>(systemTime(SYSTEM_TIME_REALTIME) -
+                                              systemTime(SYSTEM_TIME_MONOTONIC));
     proto.set_real_to_elapsed_time_offset_nanos(timeOffsetNs);
     proto.set_version(TRACING_VERSION);
     return proto;
@@ -206,11 +285,34 @@
 
         std::string serializedProto;
         entryProto.SerializeToString(&serializedProto);
-        entryProto.Clear();
+
+        TransactionDataSource::Trace([&](TransactionDataSource::TraceContext context) {
+            // In "active" mode write each committed transaction to perfetto.
+            // Note: the starting state is written (once) when the perfetto "start" event is
+            // received.
+            if (context.GetCustomTlsState()->mMode != Mode::MODE_ACTIVE) {
+                return;
+            }
+            {
+                auto packet = context.NewTracePacket();
+                packet->set_timestamp(static_cast<uint64_t>(entryProto.elapsed_realtime_nanos()));
+                packet->set_timestamp_clock_id(perfetto::protos::pbzero::BUILTIN_CLOCK_MONOTONIC);
+                auto* transactions = packet->set_surfaceflinger_transactions();
+                transactions->AppendRawProtoBytes(serializedProto.data(), serializedProto.size());
+            }
+            {
+                // TODO (b/162206162): remove empty packet when perfetto bug is fixed.
+                //  It is currently needed in order not to lose the last trace entry.
+                context.NewTracePacket();
+            }
+        });
+
         std::vector<std::string> entries = mBuffer.emplace(std::move(serializedProto));
         removedEntries.reserve(removedEntries.size() + entries.size());
         removedEntries.insert(removedEntries.end(), std::make_move_iterator(entries.begin()),
                               std::make_move_iterator(entries.end()));
+
+        entryProto.Clear();
     }
 
     perfetto::protos::TransactionTraceEntry removedEntryProto;
@@ -309,44 +411,38 @@
     }
 }
 
-void TransactionTracing::addStartingStateToProtoLocked(
-        perfetto::protos::TransactionTraceFile& proto) {
-    if (mStartingStates.size() == 0) {
-        return;
+std::optional<perfetto::protos::TransactionTraceEntry>
+TransactionTracing::createStartingStateProtoLocked() {
+    if (mStartingStates.empty()) {
+        return std::nullopt;
     }
 
-    perfetto::protos::TransactionTraceEntry* entryProto = proto.add_entry();
-    entryProto->set_elapsed_realtime_nanos(mStartingTimestamp);
-    entryProto->set_vsync_id(0);
+    perfetto::protos::TransactionTraceEntry entryProto;
+    entryProto.set_elapsed_realtime_nanos(mStartingTimestamp);
+    entryProto.set_vsync_id(0);
 
-    entryProto->mutable_added_layers()->Reserve(static_cast<int32_t>(mStartingStates.size()));
+    entryProto.mutable_added_layers()->Reserve(static_cast<int32_t>(mStartingStates.size()));
     for (auto& [layerId, state] : mStartingStates) {
-        entryProto->mutable_added_layers()->Add(mProtoParser.toProto(state.args));
+        entryProto.mutable_added_layers()->Add(mProtoParser.toProto(state.args));
     }
 
     perfetto::protos::TransactionState transactionProto = mProtoParser.toProto(mStartingStates);
     transactionProto.set_vsync_id(0);
     transactionProto.set_post_time(mStartingTimestamp);
-    entryProto->mutable_transactions()->Add(std::move(transactionProto));
+    entryProto.mutable_transactions()->Add(std::move(transactionProto));
 
-    entryProto->mutable_destroyed_layer_handles()->Reserve(
+    entryProto.mutable_destroyed_layer_handles()->Reserve(
             static_cast<int32_t>(mRemovedLayerHandlesAtStart.size()));
     for (const uint32_t destroyedLayerHandleId : mRemovedLayerHandlesAtStart) {
-        entryProto->mutable_destroyed_layer_handles()->Add(destroyedLayerHandleId);
+        entryProto.mutable_destroyed_layer_handles()->Add(destroyedLayerHandleId);
     }
 
-    entryProto->mutable_displays()->Reserve(static_cast<int32_t>(mStartingDisplayInfos.size()));
+    entryProto.mutable_displays()->Reserve(static_cast<int32_t>(mStartingDisplayInfos.size()));
     for (auto& [layerStack, displayInfo] : mStartingDisplayInfos) {
-        entryProto->mutable_displays()->Add(mProtoParser.toProto(displayInfo, layerStack.id));
+        entryProto.mutable_displays()->Add(mProtoParser.toProto(displayInfo, layerStack.id));
     }
-}
 
-perfetto::protos::TransactionTraceFile TransactionTracing::writeToProto() {
-    std::scoped_lock<std::mutex> lock(mTraceLock);
-    perfetto::protos::TransactionTraceFile proto = createTraceFileProto();
-    addStartingStateToProtoLocked(proto);
-    mBuffer.writeToProto(proto);
-    return proto;
+    return entryProto;
 }
 
 } // namespace android
diff --git a/services/surfaceflinger/Tracing/TransactionTracing.h b/services/surfaceflinger/Tracing/TransactionTracing.h
index 09fcd8a..ddbf3e4 100644
--- a/services/surfaceflinger/Tracing/TransactionTracing.h
+++ b/services/surfaceflinger/Tracing/TransactionTracing.h
@@ -22,8 +22,8 @@
 #include <utils/Singleton.h>
 #include <utils/Timers.h>
 
-#include <memory>
 #include <mutex>
+#include <optional>
 #include <thread>
 
 #include "FrontEnd/DisplayInfo.h"
@@ -41,7 +41,7 @@
 class TransactionTracingTest;
 
 /*
- * Records all committed transactions into a ring bufffer.
+ * Records all committed transactions into a ring buffer.
  *
  * Transactions come in via the binder thread. They are serialized to proto
  * and stored in a map using the transaction id as key. Main thread will
@@ -49,26 +49,104 @@
  * the tracing thread. The tracing thread will then wake up and add the
  * committed transactions to the ring buffer.
  *
- * When generating SF dump state, we will flush the buffer to a file which
- * will then be included in the bugreport.
+ * The traced data can then be collected via:
+ * - Perfetto (preferred).
+ * - File system, after triggering the disk write through SF backdoor. This is legacy and is going
+ *   to be phased out.
+ *
+ * The Perfetto custom data source TransactionDataSource is registered with perfetto and is used
+ * to listen to perfetto events (setup, start, stop, flush) and to write trace packets to perfetto.
+ *
+ * The user can configure/start/stop tracing via /system/bin/perfetto.
+ *
+ * Tracing can operate in the following modes.
+ *
+ * ACTIVE mode:
+ * The transactions ring buffer (starting state + following committed transactions) is written
+ * (only once) to perfetto when the 'start' event is received.
+ * Transactions are then written to perfetto each time they are committed.
+ * On the receiver side, the data source is to be configured to periodically
+ * flush data to disk providing virtually infinite storage.
+ *
+ * CONTINUOUS mode:
+ * Listens to the perfetto 'flush' event (e.g. when a bugreport is taken).
+ * When a 'flush' event is received, the ring buffer of transactions (starting state + following
+ * committed transactions) is written to perfetto. On the receiver side, the data source is to be
+ * configured with a dedicated buffer large enough to store all the flushed data.
+ *
+ *
+ * E.g. start active mode tracing:
+ *
+   adb shell perfetto \
+     -c - --txt \
+     -o /data/misc/perfetto-traces/trace \
+   <<EOF
+   unique_session_name: "surfaceflinger_transactions_active"
+   buffers: {
+       size_kb: 1024
+       fill_policy: RING_BUFFER
+   }
+   data_sources: {
+       config {
+           name: "android.surfaceflinger.transactions"
+           surfaceflinger_transactions_config: {
+               mode: MODE_ACTIVE
+           }
+       }
+   }
+   write_into_file: true
+   file_write_period_ms: 100
+   EOF
+ *
+ *
+ * E.g. start continuous mode tracing:
+ *
+   adb shell perfetto \
+     -c - --txt \
+     -o /data/misc/perfetto-traces/trace \
+   <<EOF
+   unique_session_name: "surfaceflinger_transactions_continuous"
+   buffers: {
+       size_kb: 1024
+       fill_policy: RING_BUFFER
+   }
+   data_sources: {
+       config {
+           name: "android.surfaceflinger.transactions"
+           surfaceflinger_transactions_config: {
+               mode: MODE_CONTINUOUS
+           }
+       }
+   }
+   EOF
  *
  */
 class TransactionTracing {
 public:
+    using Mode = perfetto::protos::pbzero::SurfaceFlingerTransactionsConfig::Mode;
+
     TransactionTracing();
     ~TransactionTracing();
 
+    // Start event from perfetto data source
+    void onStart(Mode mode);
+    // Flush event from perfetto data source
+    void onFlush(Mode mode);
+
     void addQueuedTransaction(const TransactionState&);
     void addCommittedTransactions(int64_t vsyncId, nsecs_t commitTime, frontend::Update& update,
                                   const frontend::DisplayInfos&, bool displayInfoChanged);
     status_t writeToFile(const std::string& filename = FILE_PATH);
+    // Return buffer contents as trace file proto
+    perfetto::protos::TransactionTraceFile writeToProto() EXCLUDES(mMainThreadLock);
     void setBufferSize(size_t bufferSizeInBytes);
     void onLayerRemoved(int layerId);
     void dump(std::string&) const;
     // Wait until all the committed transactions for the specified vsync id are added to the buffer.
     void flush() EXCLUDES(mMainThreadLock);
+
     static constexpr auto CONTINUOUS_TRACING_BUFFER_SIZE = 512 * 1024;
-    static constexpr auto ACTIVE_TRACING_BUFFER_SIZE = 100 * 1024 * 1024;
+    static constexpr auto LEGACY_ACTIVE_TRACING_BUFFER_SIZE = 100 * 1024 * 1024;
     // version 1 - switching to support new frontend
     static constexpr auto TRACING_VERSION = 1;
 
@@ -88,7 +166,6 @@
     TransactionRingBuffer<perfetto::protos::TransactionTraceFile,
                           perfetto::protos::TransactionTraceEntry>
             mBuffer GUARDED_BY(mTraceLock);
-    size_t mBufferSizeInBytes GUARDED_BY(mTraceLock) = CONTINUOUS_TRACING_BUFFER_SIZE;
     std::unordered_map<uint64_t, perfetto::protos::TransactionState> mQueuedTransactions
             GUARDED_BY(mTraceLock);
     LocklessStack<perfetto::protos::TransactionState> mTransactionQueue;
@@ -124,19 +201,17 @@
     std::vector<uint32_t /* layerId */> mPendingDestroyedLayers; // only accessed by main thread
     int64_t mLastUpdatedVsyncId = -1;
 
+    void writeRingBufferToPerfetto(TransactionTracing::Mode mode);
     perfetto::protos::TransactionTraceFile createTraceFileProto() const;
     void loop();
     void addEntry(const std::vector<CommittedUpdates>& committedTransactions,
                   const std::vector<uint32_t>& removedLayers) EXCLUDES(mTraceLock);
     int32_t getLayerIdLocked(const sp<IBinder>& layerHandle) REQUIRES(mTraceLock);
     void tryPushToTracingThread() EXCLUDES(mMainThreadLock);
-    void addStartingStateToProtoLocked(perfetto::protos::TransactionTraceFile& proto)
+    std::optional<perfetto::protos::TransactionTraceEntry> createStartingStateProtoLocked()
             REQUIRES(mTraceLock);
     void updateStartingStateLocked(const perfetto::protos::TransactionTraceEntry& entry)
             REQUIRES(mTraceLock);
-    // TEST
-    // Return buffer contents as trace file proto
-    perfetto::protos::TransactionTraceFile writeToProto() EXCLUDES(mMainThreadLock);
 };
 
 class TransactionTraceWriter : public Singleton<TransactionTraceWriter> {