Add flag for drawing layers to screen with Ganesh

cc/resources/tile_manager.cc

Index: cc/resources/tile_manager.cc
diff --git a/cc/resources/tile_manager.cc b/cc/resources/tile_manager.cc
index efa914fbe479c91a4e38444da42bf85582ef8d3a..aabde7760f4f8a110dbfcd14fa99cf34bc0fa3a0 100644
--- a/cc/resources/tile_manager.cc
+++ b/cc/resources/tile_manager.cc
@@ -11,7 +11,6 @@
 #include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
-#include "cc/debug/debug_colors.h"
 #include "cc/debug/devtools_instrumentation.h"
 #include "cc/debug/traced_value.h"
 #include "cc/resources/raster_worker_pool.h"
@@ -908,14 +907,9 @@ void TileManager::RunRasterTask(
   SkDevice device(bitmap);
   SkCanvas canvas(&device);
 
-#ifndef NDEBUG
-  // Any non-painted areas will be left in this color.
-  canvas.clear(DebugColors::NonPaintedFillColor());
-#endif  // NDEBUG
-
   if (stats_instrumentation->record_rendering_stats()) {
     PicturePileImpl::RasterStats raster_stats;
-    picture_pile->Raster(&canvas, rect, contents_scale, &raster_stats);
+    picture_pile->RasterToBitmap(&canvas, rect, contents_scale, &raster_stats);
     stats_instrumentation->AddRaster(
         raster_stats.total_rasterize_time,
         raster_stats.best_rasterize_time,
@@ -929,7 +923,7 @@ void TileManager::RunRasterTask(
         100000,
         100);
   } else {
-    picture_pile->Raster(&canvas, rect, contents_scale, NULL);
+    picture_pile->RasterToBitmap(&canvas, rect, contents_scale, NULL);
   }
 }