cc: Parameterize the main thread task runner

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 c70e95d9ebc68cfae93df0c40ea9c263e063779c..7dd6752c5e4e5c39357947c7c3ca16a717017dc3 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -22,14 +22,18 @@ namespace cc {
 
 scoped_ptr<Proxy> SingleThreadProxy::Create(
     LayerTreeHost* layer_tree_host,
-    LayerTreeHostSingleThreadClient* client) {
+    LayerTreeHostSingleThreadClient* client,
+    scoped_refptr<base::SingleThreadTaskRunner> main_task_runner) {
   return make_scoped_ptr(
-      new SingleThreadProxy(layer_tree_host, client)).PassAs<Proxy>();
+             new SingleThreadProxy(layer_tree_host, client, main_task_runner))
+      .PassAs<Proxy>();
 }
 
-SingleThreadProxy::SingleThreadProxy(LayerTreeHost* layer_tree_host,
-                                     LayerTreeHostSingleThreadClient* client)
-    : Proxy(NULL),
+SingleThreadProxy::SingleThreadProxy(
+    LayerTreeHost* layer_tree_host,
+    LayerTreeHostSingleThreadClient* client,
+    scoped_refptr<base::SingleThreadTaskRunner> main_task_runner)
+    : Proxy(main_task_runner, NULL),
       layer_tree_host_(layer_tree_host),
       client_(client),
       next_frame_is_newly_committed_frame_(false),