cc: Free gpu resources when we are invisible or TM is oom.

cc/resources/rasterizer.h

Index: cc/resources/rasterizer.h
diff --git a/cc/resources/rasterizer.h b/cc/resources/rasterizer.h
index 43df0b0c3d9ba9c4db27e354b6271a0322fe2bbc..301c3d5141c500174f312b21b16f37b0fbbb8412 100644
--- a/cc/resources/rasterizer.h
+++ b/cc/resources/rasterizer.h
@@ -34,6 +34,8 @@ class CC_EXPORT Rasterizer {
       ResourcePool* resource_pool,
       ResourceFormat resource_format,
       const UpdateTileDrawInfoCallback& update_tile_draw_info) = 0;
+  virtual void ClearCache() = 0;
+  virtual void RestoreCacheLimits() = 0;
 
  protected:
   Rasterizer() {}