Remove the default format from ResourcePool.

cc/resources/tile_task_runner.h

Index: cc/resources/tile_task_runner.h
diff --git a/cc/resources/tile_task_runner.h b/cc/resources/tile_task_runner.h
index 1de0f4f54dad8bb387cb5e25698c2a6c12cb5e96..a27957d7cc92421b9dcb8a517b2ee46de41fb92a 100644
--- a/cc/resources/tile_task_runner.h
+++ b/cc/resources/tile_task_runner.h
@@ -160,6 +160,9 @@ class CC_EXPORT TileTaskRunner {
   // Check for completed tasks and dispatch reply callbacks.
   virtual void CheckForCompletedTasks() = 0;
 
+  // Returns the most appropriate format to use.

[reveman, 2015/01/23 16:41:42]

nit: Sounds like it would be ok to use a different format and ignore the return
value of this function. That's not really the case, is it? Should we make it
clear that it's required to use the format returned by this function?

[peterp, 2015/01/26 17:05:28]

In the current version of the code it needs to use this format.

Later on, that's only going to be true for the hardware rasterizer. With tile
compression and the software rasterizer enabled it may use different formats
depending on the tile.

I'll change the comment.

+  virtual ResourceFormat GetResourceFormat() = 0;
+
  protected:
   virtual ~TileTaskRunner() {}
 };