The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/43f89e492ac625dd1e7e12a9ab2ee66282ddb31d

commit 43f89e492ac625dd1e7e12a9ab2ee66282ddb31d
Author: mcasas <mcasas@chromium.org>
Date: Sat Oct 15 02:12:45 2016

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

This CL limits to one the amount of grab-frame operations in
flight by adding a flag to ImageCaptureFrameGrabber, this
prevents hitting a DCHECK in debug, or doing wrong things
in !DCHECK_IS_ON() builds.

It also adds a content_browsertest for grabFrame() and
refactors the operations in that file a bit.

BUG= 655900 
TEST=see bug for reproduction cases

Review-Url: https://codereview.chromium.org/2418923003
Cr-Commit-Position: refs/heads/master@{#425535}

[modify] https://crrev.com/43f89e492ac625dd1e7e12a9ab2ee66282ddb31d/content/browser/webrtc/webrtc_image_capture_browsertest.cc
[modify] https://crrev.com/43f89e492ac625dd1e7e12a9ab2ee66282ddb31d/content/renderer/media/image_capture_frame_grabber.cc
[modify] https://crrev.com/43f89e492ac625dd1e7e12a9ab2ee66282ddb31d/content/renderer/media/image_capture_frame_grabber.h
[modify] https://crrev.com/43f89e492ac625dd1e7e12a9ab2ee66282ddb31d/content/test/data/media/image_capture_test.html