base: Make it possible to replace the MessageLoop's task runner

base/message_loop/message_loop_task_runner.h

Index: base/message_loop/message_loop_task_runner.h
diff --git a/base/message_loop/message_loop_task_runner.h b/base/message_loop/message_loop_task_runner.h
index dc2947df26c618f8204581c55a807a57ad40df6a..8be534a499dbbe62afbf1a259cb88b6b725be018 100644
--- a/base/message_loop/message_loop_task_runner.h
+++ b/base/message_loop/message_loop_task_runner.h
@@ -7,8 +7,8 @@
 
 #include "base/base_export.h"
 #include "base/memory/ref_counted.h"
+#include "base/message_loop/bindable_single_thread_task_runner.h"
 #include "base/pending_task.h"
-#include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/platform_thread.h"
 
@@ -17,18 +17,17 @@ namespace internal {
 
 class IncomingTaskQueue;
 
-// A stock implementation of SingleThreadTaskRunner that is created and managed
-// by a MessageLoop. For now a MessageLoopTaskRunner can only be created as
-// part of a MessageLoop.
-class BASE_EXPORT MessageLoopTaskRunner : public SingleThreadTaskRunner {
+// A stock implementation of BindableSingleThreadTaskRunner that is created and
+// managed by a MessageLoop. For now a MessageLoopTaskRunner can only be
+// created as part of a MessageLoop.
+class BASE_EXPORT MessageLoopTaskRunner
+    : public BindableSingleThreadTaskRunner {
  public:
   explicit MessageLoopTaskRunner(
       scoped_refptr<IncomingTaskQueue> incoming_queue);
 
-  // Initialize this message loop task runner on the current thread.
-  void BindToCurrentThread();
-
-  // SingleThreadTaskRunner implementation
+  // BindableSingleThreadTaskRunner implementation
+  void BindToCurrentThread() override;
   bool PostDelayedTask(const tracked_objects::Location& from_here,
                        const base::Closure& task,
                        base::TimeDelta delay) override;