GitLab

Implement SetVisuallyDeemphasized in ChromeRenderViewObserver
- Add a ChromeViewMsg_SetVisuallyDeemphasized and use it to toggle background dimming on web contents via ChromeRenderViewObserver;
- Derive WebViewColorOverlay from WebKit::WebPageOverlay and add to web view when need to dimming the background;
- Remove RWHV SetVisuallyDeemphasized since it's no longer used;

BUG=103386
TEST=Verify fix for 103386, dimming should show up even when accelerated compositing is on.


Review URL: http://codereview.chromium.org/8730001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112787 0039d316-1c4b-4281-b951-d872f2087c98