cc: Remove use of PassAs() and constructor-casting with scoped_ptr.

cc/test/fake_tile_manager.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/test/fake_tile_manager.h"
 
 #include <deque>
 
 #include "base/lazy_instance.h"
 #include "cc/resources/raster_buffer.h"
@@ skipping 33 matching lines @@
       task->DidComplete();
 
       task->RunReplyOnOriginThread();
     }
     completed_tasks_.clear();
   }
 
   // Overridden from RasterizerTaskClient:
   virtual scoped_ptr<RasterBuffer> AcquireBufferForRaster(
       const Resource* resource) OVERRIDE {
-    return scoped_ptr<RasterBuffer>();
+    return nullptr;
   }
   virtual void ReleaseBufferForRaster(
       scoped_ptr<RasterBuffer> buffer) OVERRIDE {}
 
  private:
   RasterTask::Vector completed_tasks_;
 };
 base::LazyInstance<FakeRasterizerImpl> g_fake_rasterizer =
     LAZY_INSTANCE_INITIALIZER;
 
@@ skipping 33 matching lines @@
 }
 
 void FakeTileManager::Release(Tile* tile) {
   TileManager::Release(tile);
 
   FreeResourcesForReleasedTiles();
   CleanUpReleasedTiles();
 }
 
 }  // namespace cc