[DevTools] Use device metrics emulation implemented in content.

Source/core/page/Settings.in

Index: Source/core/page/Settings.in
diff --git a/Source/core/page/Settings.in b/Source/core/page/Settings.in
index 5383a4a0405394218aa45a557294b962ed3daca7..34e448e3f51fa05bf5e28f06f6ef29054bb30c80 100644
--- a/Source/core/page/Settings.in
+++ b/Source/core/page/Settings.in
@@ -150,3 +150,5 @@ touchEditingEnabled initial=false
 experimentalWebSocketEnabled initial=false
 pinchVirtualViewportEnabled initial=false
 useSolidColorScrollbars initial=false
+
+rootLayerClipsContent initial=true

[aelias_OOO_until_Jul13, 2013/10/01 08:08:51]

If your Blink patch lands first, it will break Android until the Chromium side
lands (Android requires the clip to be disabled, other platforms don't care one
way or the other).  To avoid that situation I recommend setting the default to
false, and set it to true on non-Android on the Chromium side.

I also recommend setting the layout test expectations I touched in
https://chromiumcodereview.appspot.com/19019004 as NeedsManualRebaseline, as
they'll break again when the setting goes to true on desktop platforms.

[dgozman, 2013/10/01 15:26:34]

I will first land API change (https://codereview.chromium.org/24272003/), with
setting introduced there.
Then chromium-side change, which will set it to false on Android. And only after
that this change, which uses it.

Thank for layout test expectations tip!