cc: Remove cc::Thread and cc::ThreadImpl.

cc/trees/single_thread_proxy.cc

Index: cc/trees/single_thread_proxy.cc
diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index 00bd8d13e8ca088c2354352ffaaa1e94e7147160..92b7b68157142de9f282d6af92b9a9f8034a0c7b 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -6,7 +6,6 @@
 
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
-#include "cc/base/thread.h"
 #include "cc/output/context_provider.h"
 #include "cc/output/output_surface.h"
 #include "cc/quads/draw_quad.h"
@@ -23,7 +22,7 @@ scoped_ptr<Proxy> SingleThreadProxy::Create(LayerTreeHost* layer_tree_host) {
 }
 
 SingleThreadProxy::SingleThreadProxy(LayerTreeHost* layer_tree_host)
-    : Proxy(scoped_ptr<Thread>()),
+    : Proxy(NULL),
       layer_tree_host_(layer_tree_host),
       created_offscreen_context_provider_(false),
       next_frame_is_newly_committed_frame_(false),
@@ -194,7 +193,7 @@ void SingleThreadProxy::DoCommit(scoped_ptr<ResourceUpdateQueue> queue) {
     scoped_ptr<ResourceUpdateController> update_controller =
         ResourceUpdateController::Create(
             NULL,
-            Proxy::MainThread()->TaskRunner(),
+            Proxy::MainThreadTaskRunner(),
             queue.Pass(),
             layer_tree_host_impl_->resource_provider());
     update_controller->Finalize();