Add a runtime flag in WebRuntimeFeatures to enable 'image/webp' accept header
BUG=169182

Review URL: https://chromiumcodereview.appspot.com/13814024

git-svn-id: svn://svn.chromium.org/blink/trunk@148318 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Revert 148220 "Update scrollbars on pageScaleFactor change"

> Update scrollbars on pageScaleFactor change
> 
> Calls updateScrollbars() when pageScaleFactor changed.
> Changed updateScrollbars() to avoid unnecessary relayout for overlay scrollbars.
> 
> BUG=181315
> TEST=WebFrameTest.setPageScaleFactorWithOverlayScrollbarsDoesNotLayout, WebFrameTest.pageScaleFactorUpdatesScrollbars
> 
> Review URL: https://chromiumcodereview.appspot.com/13671002

TBR=wangxianzhu@chromium.org
Review URL: https://codereview.chromium.org/14222011

git-svn-id: svn://svn.chromium.org/blink/trunk@148319 bbb929c8-8fbe-4397-9dbb-9b2b20218538