Added preliminary support for tile rasterization with Ganesh

cc/resources/raster_mode.h

Index: cc/resources/raster_mode.h
diff --git a/cc/resources/raster_mode.h b/cc/resources/raster_mode.h
index 9868059e0b7015c5a885ed92adc117d3e08fb176..2457aa7b804ebde9e6591a6e567c14ae3cb87e40 100644
--- a/cc/resources/raster_mode.h
+++ b/cc/resources/raster_mode.h
@@ -21,7 +21,8 @@ enum RasterMode {
   HIGH_QUALITY_NO_LCD_RASTER_MODE = 0,
   HIGH_QUALITY_RASTER_MODE = 1,
   LOW_QUALITY_RASTER_MODE = 2,
-  NUM_RASTER_MODES = 3
+  GPU_RASTER_MODE = 3,
+  NUM_RASTER_MODES = 4
 };
 
 scoped_ptr<base::Value> RasterModeAsValue(RasterMode mode);