[Mojo Video Capture] Replace RESOURCE_UTILIZATION with interface ReceiverLoadObserver

media/capture/content/screen_capture_device_core.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/capture/content/screen_capture_device_core.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 95 matching lines @@
     return;
 
   oracle_proxy_->Stop();
   oracle_proxy_ = NULL;
 
   TransitionStateTo(kIdle);
 
   capture_machine_->Stop(base::Bind(&base::DoNothing));
 }
 
+void ScreenCaptureDeviceCore::OnConsumerReportingUtilization(
+    int frame_id,
+    double utilization) {
+  oracle_proxy_->OnConsumerReportingUtilization(frame_id, utilization);

[miu, 2016/12/01 05:25:18]

Could |oracle_proxy_| be null here? Not sure whether to:

1. DCHECK(oracle_proxy_);

or

2. if (state != kCapturing && state_ != kSuspended)
     return;

[chfremer, 2016/12/02 01:28:28]

Thanks for raising this.
This makes me realize that it is not a good idea to have this method be called
from threads other than the other methods (probably the "device thread"). I now
made changes to the factory logic in VideoCaptureManager and
VideoCaptureController to ensure that consumer utilization is always reported on
the device thread.

With this change, it should be guaranteed that no utilization reports arrive
after StopAndDeAllicate has been called. Therefore, I am going to opt for a
DCHECK.

+}
+
 void ScreenCaptureDeviceCore::CaptureStarted(bool success) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!success)
     Error(FROM_HERE, "Failed to start capture machine.");
 }
 
 ScreenCaptureDeviceCore::ScreenCaptureDeviceCore(
     std::unique_ptr<VideoCaptureMachine> capture_machine)
     : state_(kIdle), capture_machine_(std::move(capture_machine)) {
   DCHECK(capture_machine_.get());
@@ skipping 32 matching lines @@
     return;
 
   if (oracle_proxy_.get())
     oracle_proxy_->ReportError(from_here, reason);
 
   StopAndDeAllocate();
   TransitionStateTo(kError);
 }
 
 }  // namespace media