Introduce separate client and init path for single-threaded cc

cc/layers/tiled_layer_unittest.cc

 // Copyright 2011 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/tiled_layer.h"
 
 #include <limits>
 #include <vector>
 
 #include "cc/debug/overdraw_metrics.h"
@@ skipping 41 matching lines @@
         queue_(make_scoped_ptr(new ResourceUpdateQueue)),
         impl_thread_("ImplThread"),
         fake_layer_tree_host_client_(FakeLayerTreeHostClient::DIRECT_3D),
         occlusion_(NULL) {
     settings_.max_partial_texture_updates = std::numeric_limits<size_t>::max();
     settings_.layer_transforms_should_scale_layer_contents = true;
   }
 
   virtual void SetUp() {
     impl_thread_.Start();
-    layer_tree_host_ = LayerTreeHost::Create(&fake_layer_tree_host_client_,
-                                             NULL,
-                                             settings_,
-                                             impl_thread_.message_loop_proxy());
+    layer_tree_host_ = LayerTreeHost::CreateThreaded(
+        &fake_layer_tree_host_client_,
+        NULL,
+        settings_,
+        impl_thread_.message_loop_proxy());
     proxy_ = layer_tree_host_->proxy();
     resource_manager_ = PrioritizedResourceManager::Create(proxy_);
     layer_tree_host_->SetLayerTreeHostClientReady();
     layer_tree_host_->InitializeOutputSurfaceIfNeeded();
     layer_tree_host_->SetRootLayer(Layer::Create());
 
     CHECK(output_surface_->BindToClient(&output_surface_client_));
 
     DebugScopedSetImplThreadAndMainThreadBlocked
         impl_thread_and_main_thread_blocked(proxy_);
@@ skipping 1870 matching lines @@
   // Invalidate the entire layer in layer space. When painting, the rect given
   // to webkit should match the layer's bounds.
   layer->SetNeedsDisplayRect(layer_rect);
   layer->Update(queue_.get(), NULL);
 
   EXPECT_RECT_EQ(layer_rect, layer->tracking_layer_painter()->PaintedRect());
 }
 
 }  // namespace
 }  // namespace cc