Force on partial raster for layout tests.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index b7786ec809bfc5444b2074a6dd0e55fd19260d21..d31b795b17e29e2b3b1c3bd13e9e0c4a6c1d9490 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -225,10 +225,13 @@ const char kDisableNativeGpuMemoryBuffers[] =
 // Disables the Web Notification and the Push APIs.
 const char kDisableNotifications[]          = "disable-notifications";
 
-// Disable partial raster in renderer. Disabling this switch also disables
+// Disable partial raster in the renderer. Disabling this switch also disables
 // the use of persistent gpu memory buffers.
 const char kDisablePartialRaster[] = "disable-partial-raster";
 
+// Enable partial raster in the renderer.
+const char kEnablePartialRaster[] = "enable-partial-raster";
+
 // Disable Pepper3D.
 const char kDisablePepper3d[]               = "disable-pepper-3d";