diff --git a/services/mediaresourcemanager/ResourceObserverService.cpp b/services/mediaresourcemanager/ResourceObserverService.cpp
new file mode 100644
index 0000000..7c4c875
--- /dev/null
+++ b/services/mediaresourcemanager/ResourceObserverService.cpp
@@ -0,0 +1,312 @@
+/**
+ *
+ * Copyright 2020, 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.
+ */
+
+//#define LOG_NDEBUG 0
+#define LOG_TAG "ResourceObserverService"
+#include <utils/Log.h>
+
+#include <android/binder_manager.h>
+#include <android/binder_process.h>
+#include <binder/IServiceManager.h>
+#include <utils/String16.h>
+#include <aidl/android/media/MediaResourceParcel.h>
+
+#include "ResourceObserverService.h"
+
+namespace aidl {
+namespace android {
+namespace media {
+bool operator<(const MediaObservableFilter& lhs, const MediaObservableFilter &rhs) {
+    return lhs.type < rhs.type || (lhs.type == rhs.type && lhs.eventFilter < rhs.eventFilter);
+}
+}}} // namespace ::aidl::android::media
+
+namespace android {
+
+using ::aidl::android::media::MediaResourceParcel;
+using ::aidl::android::media::MediaObservableEvent;
+
+// MediaObservableEvent will be used as uint64_t flags.
+static_assert(sizeof(MediaObservableEvent) == sizeof(uint64_t));
+
+static std::vector<MediaObservableEvent> sEvents = {
+        MediaObservableEvent::kBusy,
+        MediaObservableEvent::kIdle,
+};
+
+static MediaObservableType getObservableType(const MediaResourceParcel& res) {
+    if (res.subType == MediaResourceSubType::kVideoCodec) {
+        if (res.type == MediaResourceType::kNonSecureCodec) {
+            return MediaObservableType::kVideoNonSecureCodec;
+        }
+        if (res.type == MediaResourceType::kSecureCodec) {
+            return MediaObservableType::kVideoSecureCodec;
+        }
+    }
+    return MediaObservableType::kInvalid;
+}
+
+//static
+std::mutex ResourceObserverService::sDeathRecipientLock;
+//static
+std::map<uintptr_t, std::shared_ptr<ResourceObserverService::DeathRecipient> >
+ResourceObserverService::sDeathRecipientMap;
+
+struct ResourceObserverService::DeathRecipient {
+    DeathRecipient(ResourceObserverService* _service,
+            const std::shared_ptr<IResourceObserver>& _observer)
+        : service(_service), observer(_observer) {}
+    ~DeathRecipient() {}
+
+    void binderDied() {
+        if (service != nullptr) {
+            service->unregisterObserver(observer);
+        }
+    }
+
+    ResourceObserverService* service;
+    std::shared_ptr<IResourceObserver> observer;
+};
+
+// static
+void ResourceObserverService::BinderDiedCallback(void* cookie) {
+    uintptr_t id = reinterpret_cast<uintptr_t>(cookie);
+
+    ALOGW("Observer %lld is dead", (long long)id);
+
+    std::shared_ptr<DeathRecipient> recipient;
+
+    {
+        std::scoped_lock lock{sDeathRecipientLock};
+
+        auto it = sDeathRecipientMap.find(id);
+        if (it != sDeathRecipientMap.end()) {
+            recipient = it->second;
+        }
+    }
+
+    if (recipient != nullptr) {
+        recipient->binderDied();
+    }
+}
+
+//static
+std::shared_ptr<ResourceObserverService> ResourceObserverService::instantiate() {
+    std::shared_ptr<ResourceObserverService> observerService =
+            ::ndk::SharedRefBase::make<ResourceObserverService>();
+    binder_status_t status = AServiceManager_addService(observerService->asBinder().get(),
+            ResourceObserverService::getServiceName());
+    if (status != STATUS_OK) {
+        return nullptr;
+    }
+    return observerService;
+}
+
+ResourceObserverService::ResourceObserverService()
+    : mDeathRecipient(AIBinder_DeathRecipient_new(BinderDiedCallback)) {}
+
+binder_status_t ResourceObserverService::dump(
+        int fd, const char** /*args*/, uint32_t /*numArgs*/) {
+    String8 result;
+
+    if (checkCallingPermission(String16("android.permission.DUMP")) == false) {
+        result.format("Permission Denial: "
+                "can't dump ResourceManagerService from pid=%d, uid=%d\n",
+                AIBinder_getCallingPid(),
+                AIBinder_getCallingUid());
+        write(fd, result.string(), result.size());
+        return PERMISSION_DENIED;
+    }
+
+    result.appendFormat("ResourceObserverService: %p\n", this);
+    result.appendFormat("  Registered Observers: %zu\n", mObserverInfoMap.size());
+
+    {
+        std::scoped_lock lock{mObserverLock};
+
+        for (auto &observer : mObserverInfoMap) {
+            result.appendFormat("    Observer %p:\n", observer.second.binder.get());
+            for (auto &observable : observer.second.filters) {
+                String8 enabledEventsStr;
+                for (auto &event : sEvents) {
+                    if (((uint64_t)observable.eventFilter & (uint64_t)event) != 0) {
+                        if (!enabledEventsStr.isEmpty()) {
+                            enabledEventsStr.append("|");
+                        }
+                        enabledEventsStr.append(toString(event).c_str());
+                    }
+                }
+                result.appendFormat("      %s: %s\n",
+                        toString(observable.type).c_str(), enabledEventsStr.c_str());
+            }
+        }
+    }
+
+    write(fd, result.string(), result.size());
+    return OK;
+}
+
+Status ResourceObserverService::registerObserver(
+        const std::shared_ptr<IResourceObserver>& in_observer,
+        const std::vector<MediaObservableFilter>& in_filters) {
+    // TODO(chz): Guard this by a permission.
+
+    ::ndk::SpAIBinder binder = in_observer->asBinder();
+
+    {
+        std::scoped_lock lock{mObserverLock};
+
+        if (mObserverInfoMap.find((uintptr_t)binder.get()) != mObserverInfoMap.end()) {
+            return Status::fromServiceSpecificError(ALREADY_EXISTS);
+        }
+
+        if (in_filters.empty()) {
+            return Status::fromServiceSpecificError(BAD_VALUE);
+        }
+
+        // Add observer info.
+        mObserverInfoMap.emplace((uintptr_t)binder.get(),
+                ObserverInfo{binder, in_observer, in_filters});
+
+        // Add observer to observable->subscribers map.
+        for (auto &filter : in_filters) {
+            for (auto &event : sEvents) {
+                if (!((uint64_t)filter.eventFilter & (uint64_t)event)) {
+                    continue;
+                }
+                MediaObservableFilter key{filter.type, event};
+                mObservableToSubscribersMap[key].emplace((uintptr_t)binder.get(), in_observer);
+            }
+        }
+    }
+
+    // Add death binder and link.
+    uintptr_t cookie = (uintptr_t)binder.get();
+    {
+        std::scoped_lock lock{sDeathRecipientLock};
+        sDeathRecipientMap.emplace(
+                cookie, std::make_shared<DeathRecipient>(this, in_observer));
+    }
+
+    AIBinder_linkToDeath(binder.get(), mDeathRecipient.get(),
+                         reinterpret_cast<void*>(cookie));
+
+    return Status::ok();
+}
+
+Status ResourceObserverService::unregisterObserver(
+        const std::shared_ptr<IResourceObserver>& in_observer) {
+    // TODO(chz): Guard this by a permission.
+
+    ::ndk::SpAIBinder binder = in_observer->asBinder();
+
+    {
+        std::scoped_lock lock{mObserverLock};
+
+        auto it = mObserverInfoMap.find((uintptr_t)binder.get());
+        if (it == mObserverInfoMap.end()) {
+            return Status::fromServiceSpecificError(NAME_NOT_FOUND);
+        }
+
+        // Remove observer from observable->subscribers map.
+        for (auto &filter : it->second.filters) {
+            for (auto &event : sEvents) {
+                if (!((uint64_t)filter.eventFilter & (uint64_t)event)) {
+                    continue;
+                }
+                MediaObservableFilter key{filter.type, event};
+                mObservableToSubscribersMap[key].erase((uintptr_t)binder.get());
+
+                //Remove the entry if there's no more subscribers.
+                if (mObservableToSubscribersMap[key].empty()) {
+                    mObservableToSubscribersMap.erase(key);
+                }
+            }
+        }
+
+        // Remove observer info.
+        mObserverInfoMap.erase(it);
+    }
+
+    // Unlink and remove death binder.
+    uintptr_t cookie = (uintptr_t)binder.get();
+    AIBinder_unlinkToDeath(binder.get(), mDeathRecipient.get(),
+            reinterpret_cast<void*>(cookie));
+
+    {
+        std::scoped_lock lock{sDeathRecipientLock};
+        sDeathRecipientMap.erase(cookie);
+    }
+
+    return Status::ok();
+}
+
+void ResourceObserverService::notifyObservers(
+        MediaObservableEvent event, int uid, int pid, const ResourceList &resources) {
+    struct CalleeInfo {
+        std::shared_ptr<IResourceObserver> observer;
+        std::vector<MediaObservableParcel> monitors;
+    };
+    // Build a consolidated list of observers to call with their respective observables.
+    std::map<uintptr_t, CalleeInfo> calleeList;
+
+    {
+        std::scoped_lock lock{mObserverLock};
+
+        for (auto &res : resources) {
+            // Skip if this resource doesn't map to any observable type.
+            MediaObservableType observableType = getObservableType(res.second);
+            if (observableType == MediaObservableType::kInvalid) {
+                continue;
+            }
+            MediaObservableFilter key{observableType, event};
+            // Skip if no one subscribed to this observable.
+            auto observableIt = mObservableToSubscribersMap.find(key);
+            if (observableIt == mObservableToSubscribersMap.end()) {
+                continue;
+            }
+            // Loop through all subsribers.
+            for (auto &subscriber : observableIt->second) {
+                auto calleeIt = calleeList.find(subscriber.first);
+                if (calleeIt == calleeList.end()) {
+                    calleeList.emplace(subscriber.first, CalleeInfo{
+                        subscriber.second, {{observableType, res.second.value}}});
+                } else {
+                    calleeIt->second.monitors.push_back({observableType, res.second.value});
+                }
+            }
+        }
+    }
+
+    // Finally call the observers about the status change.
+    for (auto &calleeInfo : calleeList) {
+        calleeInfo.second.observer->onStatusChanged(
+                event, uid, pid, calleeInfo.second.monitors);
+    }
+}
+
+void ResourceObserverService::onResourceAdded(
+        int uid, int pid, const ResourceList &resources) {
+    notifyObservers(MediaObservableEvent::kBusy, uid, pid, resources);
+}
+
+void ResourceObserverService::onResourceRemoved(
+        int uid, int pid, const ResourceList &resources) {
+    notifyObservers(MediaObservableEvent::kIdle, uid, pid, resources);
+}
+
+} // namespace android