cc: Parameterize the main thread task runner

cc/trees/proxy.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/trees/proxy.h"
 
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/single_thread_task_runner.h"
 
 namespace cc {
@@ skipping 48 matching lines @@
   return true;
 #endif
 }
 
 #if DCHECK_IS_ON
 void Proxy::SetMainThreadBlocked(bool is_main_thread_blocked) {
   is_main_thread_blocked_ = is_main_thread_blocked;
 }
 #endif
 
-Proxy::Proxy(scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner)
-    : main_task_runner_(base::MessageLoopProxy::current()),
+Proxy::Proxy(scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+             scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner)
 #if !DCHECK_IS_ON
-      impl_task_runner_(impl_task_runner) {
+    : main_task_runner_(main_task_runner), impl_task_runner_(impl_task_runner) {
 #else
+    : main_task_runner_(main_task_runner),
       impl_task_runner_(impl_task_runner),
       main_thread_id_(base::PlatformThread::CurrentId()),
       impl_thread_is_overridden_(false),
       is_main_thread_blocked_(false) {
 #endif
 }
 
 Proxy::~Proxy() {
   DCHECK(IsMainThread());
 }
 
 scoped_ptr<base::Value> Proxy::SchedulerAsValueForTesting() {
   return make_scoped_ptr(base::Value::CreateNullValue());
 }
 
 }  // namespace cc