cc: Do bitmap conversion for RasterBuffer in the worker thread.

cc/resources/tile_manager_perftest.cc

Index: cc/resources/tile_manager_perftest.cc
diff --git a/cc/resources/tile_manager_perftest.cc b/cc/resources/tile_manager_perftest.cc
index 211ff017906fd24d0b3eb7e1a41f6ecb732dd9b6..9f8f285741159d78c1c9835e5cad5b897e59cc6d 100644
--- a/cc/resources/tile_manager_perftest.cc
+++ b/cc/resources/tile_manager_perftest.cc
@@ -65,7 +65,7 @@ class FakeRasterizerImpl : public Rasterizer, public RasterizerTaskClient {
   }
 
   // Overridden from RasterizerTaskClient:
-  virtual SkCanvas* AcquireCanvasForRaster(RasterTask* task) OVERRIDE {
+  virtual RasterCanvas* AcquireCanvasForRaster(RasterTask* task) OVERRIDE {
     return NULL;
   }
   virtual void ReleaseCanvasForRaster(RasterTask* task) OVERRIDE {}