[DevTools] Use device metrics emulation implemented in content.

Source/core/platform/ScrollbarThemeMacCommon.mm

Index: Source/core/platform/ScrollbarThemeMacCommon.mm
===================================================================
--- Source/core/platform/ScrollbarThemeMacCommon.mm	(revision 157211)
+++ Source/core/platform/ScrollbarThemeMacCommon.mm	(working copy)
@@ -32,6 +32,7 @@
 #include "core/platform/ScrollView.h"
 #include "core/platform/ScrollbarThemeMacNonOverlayAPI.h"
 #include "core/platform/ScrollbarThemeMacOverlayAPI.h"
+#include "core/platform/ScrollbarThemeOverlay.h"
 #include "core/platform/graphics/Gradient.h"
 #include "core/platform/graphics/GraphicsContext.h"
 #include "core/platform/graphics/GraphicsContextStateSaver.h"
@@ -128,6 +129,11 @@
 
 ScrollbarTheme* ScrollbarTheme::nativeTheme()
 {
+    if (RuntimeEnabledFeatures::overlayScrollbarsEnabled()) {

[pfeldman, 2013/09/19 12:46:05]

Lets land this separately.

[dgozman, 2013/09/19 13:59:38]

Done.

+        DEFINE_STATIC_LOCAL(ScrollbarThemeOverlay, theme, (7, 0, ScrollbarThemeOverlay::AllowHitTest));
+        return &theme;
+    }
+
     if (isScrollbarOverlayAPIAvailable()) {
         DEFINE_STATIC_LOCAL(ScrollbarThemeMacOverlayAPI, theme, ());
         return &theme;