ImageCapture: avoid several grabFrame()s in flight, beef up content_browsertests

content/renderer/media/image_capture_frame_grabber.h

 // Copyright 2016 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.
 
 #ifndef CONTENT_RENDERER_MEDIA_IMAGE_CAPTURE_FRAME_GRABBER_H_
 #define CONTENT_RENDERER_MEDIA_IMAGE_CAPTURE_FRAME_GRABBER_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 28 matching lines @@
                  blink::WebImageCaptureGrabFrameCallbacks* callbacks) override;
 
  private:
   // Internal class to receive, convert and forward one frame.
   class SingleShotFrameHandler;
 
   void OnSkImage(
       ScopedWebCallbacks<blink::WebImageCaptureGrabFrameCallbacks> callbacks,
       sk_sp<SkImage> image);
 
+  // Flag to indicate that there is a frame grabbing in progress.
+  bool frame_grab_in_progress_;
+
   base::ThreadChecker thread_checker_;
   base::WeakPtrFactory<ImageCaptureFrameGrabber> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageCaptureFrameGrabber);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_IMAGE_CAPTURE_FRAME_GRABBER_H_