Enable pinch & scrollbars by default for CrOS.

cc/base/switches.cc

Index: cc/base/switches.cc
diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index 36e20ab49d52ea2106c26d68487d6faed1d7715c..5cedee9ca9d91e1b969b283cb21acff70c731f58 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -80,6 +80,10 @@ const char kMaxTilesForInterestArea[] = "max-tiles-for-interest-area";
 const char kMaxUnusedResourceMemoryUsagePercentage[] =
     "max-unused-resource-memory-usage-percentage";
 
+// Causes overlay scrollbars to appear when zoomed in ChromeOS/Windows.
+const char kEnablePinchZoomScrollbars[]     = "enable-pinch-zoom-scrollbars";
+const char kDisablePinchZoomScrollbars[]    = "disable-pinch-zoom-scrollbars";
+
 // Causes the compositor to render to textures which are then sent to the parent
 // through the texture mailbox mechanism.
 // Requires --enable-compositor-frame-message.