Don't use WebView as a proxy to show FPS counter in the compositor.

1. Move the API from WebLayerTreeView to WebWidgetClient
2. Have RenderViewImpl set the value each time a new WebFrameWidget
is attached, as in the future each one will have a new WebWidgetClient.
3. Have inspector go through the WebFrameWidget's client instead of
through WebView (and WebLayerTreeView).

Also removes the WebSetting for this, which was not used before this
CL.

R=enne@chromium.org

Change-Id: Ide83b5372033574cb965e973d50ac43d44f2e8fa
Bug: 912193
Reviewed-on: https://chromium-review.googlesource.com/c/1407633
Commit-Queue: danakj <danakj@chromium.org>
Reviewed-by: enne <enne@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623313}
14 files changed