+cc folks for awareness.

Up for code review: https://chromium-review.googlesource.com/c/chromium/src/+/890339

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/483530c1094f0ad6fe36663262b484be300f472e

commit 483530c1094f0ad6fe36663262b484be300f472e
Author: Yuri Wiitala <miu@chromium.org>
Date: Thu Feb 08 07:17:34 2018

Layer CopyOutputRequests execute in VIZ service.

Implements the final missing pieces allowing CopyOutputRequests made on
Layers to propagate and execute in the VIZ display compositor:

1. Added missing mojo fields and struct traits for viz::CopyOutputRequest
and viz::RenderPass.

2. Added extra transform code to cc::EffectTree::TakeCRsAndTransform()
to account for the scaling ratio, not just the source area.

3. Updated DelegatedFrameHost::CopyFromCompositingSurface() to use the
new scaling APIs, enabling testing and otherwise proving that all "the
plumbing" is in-place.

4. Updated RenderWidgetHostViewBrowserTests so that they now work with
--enabled-features=VizDisplayCompositor. (And, disabled dead tests I did
not feel we should bother updating; to be removed in a later change.)

5. Added privilege checks to make sure CopyOutputRequests cannot be made
from unprivileged clients. Added new RWHostImpl browser test to confirm.

Testing (all with and without --enable-features=VizDisplayCompositor):

1. All RenderWidgetHostViewBrowserTest content_browsertests pass.

2. On CrOS Ash desktop, tested CTRL-F5 (full screenshot) and
SHIFT-CTRL-F5 (partial screenshot).

3. On Linux, confirmed chrome.captureVisibleTab() screenshot API works
via the common/extensions/docs/examples/api/tabs/screenshot demo
extension.

Bug:  806375 ,  806366 ,  759310 ,  771354 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I98ad6cd90f332318dbdea9449e5d9c3a31679114
Reviewed-on: https://chromium-review.googlesource.com/890339
Commit-Queue: Yuri Wiitala <miu@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535325}
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/cc/trees/property_tree.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/common/quads/compositor_frame.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/common/quads/compositor_frame.h
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/common/quads/render_pass.h
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/service/display/surface_aggregator_unittest.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/service/frame_sinks/compositor_frame_sink_impl.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/service/frame_sinks/compositor_frame_sink_support.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/service/frame_sinks/compositor_frame_sink_support.h
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/service/frame_sinks/compositor_frame_sink_support_unittest.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/service/frame_sinks/root_compositor_frame_sink_impl.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/components/viz/test/test_layer_tree_frame_sink.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/content/browser/bad_message.h
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/content/browser/renderer_host/delegated_frame_host.cc
[add] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/content/browser/renderer_host/render_widget_host_browsertest.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/content/browser/renderer_host/render_widget_host_impl.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/content/browser/renderer_host/render_widget_host_view_browsertest.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/content/test/BUILD.gn
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/services/viz/public/cpp/compositing/copy_output_request_struct_traits.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/services/viz/public/cpp/compositing/copy_output_request_struct_traits.h
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/services/viz/public/cpp/compositing/render_pass_struct_traits.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/services/viz/public/cpp/compositing/render_pass_struct_traits.h
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/services/viz/public/cpp/compositing/struct_traits_unittest.cc
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/services/viz/public/interfaces/compositing/copy_output_request.mojom
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/services/viz/public/interfaces/compositing/render_pass.mojom
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/testing/buildbot/filters/viz.content_browsertests.filter
[modify] https://crrev.com/483530c1094f0ad6fe36663262b484be300f472e/tools/metrics/histograms/enums.xml