Assert RendererScheduler thread usage

media/video/capture/mac/video_capture_device_avfoundation_mac.mm

 // Copyright 2013 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.
 
 #import "media/video/capture/mac/video_capture_device_avfoundation_mac.h"
 
 #import <CoreVideo/CoreVideo.h>
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
@@ skipping 261 matching lines @@
 
 #pragma mark Private methods
 
 // |captureOutput| is called by the capture device to deliver a new frame.
 - (void)captureOutput:(CrAVCaptureOutput*)captureOutput
     didOutputSampleBuffer:(CoreMediaGlue::CMSampleBufferRef)sampleBuffer
            fromConnection:(CrAVCaptureConnection*)connection {
   // AVFoundation calls from a number of threads, depending on, at least, if
   // Chrome is on foreground or background. Sample the actual thread here.
   callback_thread_checker_.DetachFromThread();
-  callback_thread_checker_.CalledOnValidThread();
+  CHECK(callback_thread_checker_.CalledOnValidThread());
 
   const CoreMediaGlue::CMFormatDescriptionRef formatDescription =
       CoreMediaGlue::CMSampleBufferGetFormatDescription(sampleBuffer);
   const FourCharCode fourcc =
       CoreMediaGlue::CMFormatDescriptionGetMediaSubType(formatDescription);
   const CoreMediaGlue::CMVideoDimensions dimensions =
       CoreMediaGlue::CMVideoFormatDescriptionGetDimensions(formatDescription);
   const media::VideoCaptureFormat captureFormat(
       gfx::Size(dimensions.width, dimensions.height),
       frameRate_,
@@ skipping 49 matching lines @@
 }
 
 - (void)sendErrorString:(NSString*)error {
   DLOG(ERROR) << [error UTF8String];
   base::AutoLock lock(lock_);
   if (frameReceiver_)
     frameReceiver_->ReceiveError([error UTF8String]);
 }
 
 @end