Remove the default format from ResourcePool.

cc/test/layer_tree_test.cc

Index: cc/test/layer_tree_test.cc
diff --git a/cc/test/layer_tree_test.cc b/cc/test/layer_tree_test.cc
index 9653d8dda8a800482072ea12f4e427197f0e01f9..f0ee172ce36f9f2c272caeb57b54007d9b53408c 100644
--- a/cc/test/layer_tree_test.cc
+++ b/cc/test/layer_tree_test.cc
@@ -51,12 +51,12 @@ scoped_ptr<Rasterizer> TestHooks::CreateRasterizer(
   return host_impl->LayerTreeHostImpl::CreateRasterizer();
 }
 
-void TestHooks::CreateResourceAndTileTaskWorkerPool(
+ResourceFormat TestHooks::CreateResourceAndTileTaskWorkerPool(
     LayerTreeHostImpl* host_impl,
     scoped_ptr<TileTaskWorkerPool>* tile_task_worker_pool,
     scoped_ptr<ResourcePool>* resource_pool,
     scoped_ptr<ResourcePool>* staging_resource_pool) {
-  host_impl->LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
+  return host_impl->LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
       tile_task_worker_pool, resource_pool, staging_resource_pool);
 }
 
@@ -175,11 +175,11 @@ class LayerTreeHostImplForTesting : public LayerTreeHostImpl {
     return test_hooks_->CreateRasterizer(this);
   }
 
-  void CreateResourceAndTileTaskWorkerPool(
+  ResourceFormat CreateResourceAndTileTaskWorkerPool(
       scoped_ptr<TileTaskWorkerPool>* tile_task_worker_pool,
       scoped_ptr<ResourcePool>* resource_pool,
       scoped_ptr<ResourcePool>* staging_resource_pool) override {
-    test_hooks_->CreateResourceAndTileTaskWorkerPool(
+    return test_hooks_->CreateResourceAndTileTaskWorkerPool(
         this, tile_task_worker_pool, resource_pool, staging_resource_pool);
   }