diff --git a/common/file_fetcher.cc b/common/file_fetcher.cc
index d0a109b..3836e54 100644
--- a/common/file_fetcher.cc
+++ b/common/file_fetcher.cc
@@ -138,8 +138,9 @@
       delegate_->TransferComplete(this, true);
   } else {
     bytes_copied_ += bytes_read;
-    if (delegate_)
-      delegate_->ReceivedBytes(this, buffer_.data(), bytes_read);
+    if (delegate_ &&
+        !delegate_->ReceivedBytes(this, buffer_.data(), bytes_read))
+      return;
     ScheduleRead();
   }
 }
diff --git a/common/http_fetcher.h b/common/http_fetcher.h
index 3f7b2e8..b2fba1c 100644
--- a/common/http_fetcher.h
+++ b/common/http_fetcher.h
@@ -18,6 +18,7 @@
 #define UPDATE_ENGINE_COMMON_HTTP_FETCHER_H_
 
 #include <deque>
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -186,8 +187,9 @@
  public:
   virtual ~HttpFetcherDelegate() = default;
 
-  // Called every time bytes are received.
-  virtual void ReceivedBytes(HttpFetcher* fetcher,
+  // Called every time bytes are received. Returns false if this call causes the
+  // transfer be terminated or completed otherwise it returns true.
+  virtual bool ReceivedBytes(HttpFetcher* fetcher,
                              const void* bytes,
                              size_t length) = 0;
 
diff --git a/common/http_fetcher_unittest.cc b/common/http_fetcher_unittest.cc
index 73110e9..a0b0522 100644
--- a/common/http_fetcher_unittest.cc
+++ b/common/http_fetcher_unittest.cc
@@ -412,12 +412,13 @@
  public:
   HttpFetcherTestDelegate() = default;
 
-  void ReceivedBytes(HttpFetcher* /* fetcher */,
+  bool ReceivedBytes(HttpFetcher* /* fetcher */,
                      const void* bytes,
                      size_t length) override {
     data.append(reinterpret_cast<const char*>(bytes), length);
     // Update counters
     times_received_bytes_called_++;
+    return true;
   }
 
   void TransferComplete(HttpFetcher* fetcher, bool successful) override {
@@ -560,11 +561,13 @@
 namespace {
 class PausingHttpFetcherTestDelegate : public HttpFetcherDelegate {
  public:
-  void ReceivedBytes(HttpFetcher* fetcher,
-                     const void* /* bytes */, size_t /* length */) override {
+  bool ReceivedBytes(HttpFetcher* fetcher,
+                     const void* /* bytes */,
+                     size_t /* length */) override {
     CHECK(!paused_);
     paused_ = true;
     fetcher->Pause();
+    return true;
   }
   void TransferComplete(HttpFetcher* fetcher, bool successful) override {
     MessageLoop::current()->BreakLoop();
@@ -641,8 +644,11 @@
 namespace {
 class AbortingHttpFetcherTestDelegate : public HttpFetcherDelegate {
  public:
-  void ReceivedBytes(HttpFetcher* fetcher,
-                     const void* bytes, size_t length) override {}
+  bool ReceivedBytes(HttpFetcher* fetcher,
+                     const void* bytes,
+                     size_t length) override {
+    return true;
+  }
   void TransferComplete(HttpFetcher* fetcher, bool successful) override {
     ADD_FAILURE();  // We should never get here
     MessageLoop::current()->BreakLoop();
@@ -736,9 +742,11 @@
 namespace {
 class FlakyHttpFetcherTestDelegate : public HttpFetcherDelegate {
  public:
-  void ReceivedBytes(HttpFetcher* fetcher,
-                     const void* bytes, size_t length) override {
+  bool ReceivedBytes(HttpFetcher* fetcher,
+                     const void* bytes,
+                     size_t length) override {
     data.append(reinterpret_cast<const char*>(bytes), length);
+    return true;
   }
   void TransferComplete(HttpFetcher* fetcher, bool successful) override {
     EXPECT_TRUE(successful);
@@ -800,13 +808,15 @@
     }
   }
 
-  void ReceivedBytes(HttpFetcher* fetcher,
-                     const void* bytes, size_t length) override {
+  bool ReceivedBytes(HttpFetcher* fetcher,
+                     const void* bytes,
+                     size_t length) override {
     if (server_) {
       LOG(INFO) << "Stopping server in ReceivedBytes";
       server_.reset();
       LOG(INFO) << "server stopped";
     }
+    return true;
   }
   void TransferComplete(HttpFetcher* fetcher, bool successful) override {
     EXPECT_FALSE(successful);
@@ -974,9 +984,11 @@
  public:
   explicit RedirectHttpFetcherTestDelegate(bool expected_successful)
       : expected_successful_(expected_successful) {}
-  void ReceivedBytes(HttpFetcher* fetcher,
-                     const void* bytes, size_t length) override {
+  bool ReceivedBytes(HttpFetcher* fetcher,
+                     const void* bytes,
+                     size_t length) override {
     data.append(reinterpret_cast<const char*>(bytes), length);
+    return true;
   }
   void TransferComplete(HttpFetcher* fetcher, bool successful) override {
     EXPECT_EQ(expected_successful_, successful);
@@ -1073,10 +1085,12 @@
   explicit MultiHttpFetcherTestDelegate(int expected_response_code)
       : expected_response_code_(expected_response_code) {}
 
-  void ReceivedBytes(HttpFetcher* fetcher,
-                     const void* bytes, size_t length) override {
+  bool ReceivedBytes(HttpFetcher* fetcher,
+                     const void* bytes,
+                     size_t length) override {
     EXPECT_EQ(fetcher, fetcher_.get());
     data.append(reinterpret_cast<const char*>(bytes), length);
+    return true;
   }
 
   void TransferComplete(HttpFetcher* fetcher, bool successful) override {
@@ -1272,7 +1286,7 @@
   explicit MultiHttpFetcherTerminateTestDelegate(size_t terminate_trigger_bytes)
       : terminate_trigger_bytes_(terminate_trigger_bytes) {}
 
-  void ReceivedBytes(HttpFetcher* fetcher,
+  bool ReceivedBytes(HttpFetcher* fetcher,
                      const void* bytes,
                      size_t length) override {
     LOG(INFO) << "ReceivedBytes, " << length << " bytes.";
@@ -1285,6 +1299,7 @@
                      base::Unretained(fetcher_.get())));
     }
     bytes_downloaded_ += length;
+    return true;
   }
 
   void TransferComplete(HttpFetcher* fetcher, bool successful) override {
@@ -1338,9 +1353,11 @@
 namespace {
 class BlockedTransferTestDelegate : public HttpFetcherDelegate {
  public:
-  void ReceivedBytes(HttpFetcher* fetcher,
-                     const void* bytes, size_t length) override {
+  bool ReceivedBytes(HttpFetcher* fetcher,
+                     const void* bytes,
+                     size_t length) override {
     ADD_FAILURE();
+    return true;
   }
   void TransferComplete(HttpFetcher* fetcher, bool successful) override {
     EXPECT_FALSE(successful);
diff --git a/common/multi_range_http_fetcher.cc b/common/multi_range_http_fetcher.cc
index dc4b7c1..0a19c6a 100644
--- a/common/multi_range_http_fetcher.cc
+++ b/common/multi_range_http_fetcher.cc
@@ -86,7 +86,7 @@
 }
 
 // State change: Downloading -> Downloading or Pending transfer ended
-void MultiRangeHttpFetcher::ReceivedBytes(HttpFetcher* fetcher,
+bool MultiRangeHttpFetcher::ReceivedBytes(HttpFetcher* fetcher,
                                           const void* bytes,
                                           size_t length) {
   CHECK_LT(current_index_, ranges_.size());
@@ -99,15 +99,9 @@
                          range.length() - bytes_received_this_range_);
   }
   LOG_IF(WARNING, next_size <= 0) << "Asked to write length <= 0";
-  if (delegate_) {
-    delegate_->ReceivedBytes(this, bytes, next_size);
-    // If the transfer was already terminated by |delegate_|, return immediately
-    // to avoid calling TerminateTransfer() again.
-    if (!base_fetcher_active_) {
-      LOG(INFO) << "Delegate has terminated the transfer.";
-      return;
-    }
-  }
+  if (delegate_ && !delegate_->ReceivedBytes(this, bytes, next_size))
+    return false;
+
   bytes_received_this_range_ += length;
   if (range.HasLength() && bytes_received_this_range_ >= range.length()) {
     // Terminates the current fetcher. Waits for its TransferTerminated
@@ -115,9 +109,10 @@
     // signalling the delegate that the whole multi-transfer is complete
     // before all fetchers are really done and cleaned up.
     pending_transfer_ended_ = true;
-    LOG(INFO) << "terminating transfer";
+    LOG(INFO) << "Terminating transfer.";
     fetcher->TerminateTransfer();
   }
+  return true;
 }
 
 // State change: Downloading or Pending transfer ended -> Stopped
diff --git a/common/multi_range_http_fetcher.h b/common/multi_range_http_fetcher.h
index 54ddfbc..763c287 100644
--- a/common/multi_range_http_fetcher.h
+++ b/common/multi_range_http_fetcher.h
@@ -146,7 +146,7 @@
 
   // HttpFetcherDelegate overrides.
   // State change: Downloading -> Downloading or Pending transfer ended
-  void ReceivedBytes(HttpFetcher* fetcher,
+  bool ReceivedBytes(HttpFetcher* fetcher,
                      const void* bytes,
                      size_t length) override;