Makes tile-creation lazy

cc/layers/picture_image_layer_impl_unittest.cc

 // Copyright 2013 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/layers/picture_image_layer_impl.h"
 
 #include "cc/test/fake_impl_proxy.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
 #include "cc/test/fake_output_surface.h"
 #include "cc/test/fake_picture_layer_tiling_client.h"
@@ skipping 17 matching lines @@
       : host_impl_(ImplSidePaintingSettings(), &proxy_) {
     tiling_client_.SetTileSize(ImplSidePaintingSettings().default_tile_size);
     host_impl_.CreatePendingTree();
     host_impl_.InitializeRenderer(CreateFakeOutputSurface());
   }
 
   scoped_ptr<TestablePictureImageLayerImpl> CreateLayer(int id) {
     TestablePictureImageLayerImpl* layer =
         new TestablePictureImageLayerImpl(host_impl_.pending_tree(), id);
     layer->SetBounds(gfx::Size(100, 200));
-    layer->tilings_.reset(new PictureLayerTilingSet(&tiling_client_));
-    layer->tilings_->SetLayerBounds(layer->bounds());
+    layer->tilings_.reset(new PictureLayerTilingSet(&tiling_client_,
+                                                    layer->bounds()));
     layer->pile_ = tiling_client_.pile();
     return make_scoped_ptr(layer);
   }
 
  private:
   FakeImplProxy proxy_;
   FakeLayerTreeHostImpl host_impl_;
   FakePictureLayerTilingClient tiling_client_;
 };
 
@@ skipping 22 matching lines @@
   gfx::Size content_bounds;
   layer->CalculateContentsScale(2.f, false,
                                 &contents_scale_x, &contents_scale_y,
                                 &content_bounds);
 
   EXPECT_TRUE(layer->AreVisibleResourcesReady());
 }
 
 }  // namespace
 }  // namespace cc