Add base::RunLoop and update ui_test_utils to use it to reduce flakiness

chrome/test/base/ui_test_utils.h

Index: chrome/test/base/ui_test_utils.h
diff --git a/chrome/test/base/ui_test_utils.h b/chrome/test/base/ui_test_utils.h
index 4e2644d9470937de4fad3fcaf618c4182fd60b49..9415b825fe744aef0fd2553f86b4a4ff64443017 100644
--- a/chrome/test/base/ui_test_utils.h
+++ b/chrome/test/base/ui_test_utils.h
@@ -96,6 +96,15 @@ enum BrowserTestWaitFlags {
 // process browser tests that need to block until a condition is met.
 void RunMessageLoop();
 
+// Variant of RunMessageLoop that takes RunLoop.
+void RunRunLoop(const base::WeakPtr<MessageLoop::RunLoop>& run_loop);
+
+// Quit the given RunLoop. Allows a few generations of pending tasks to run.
+void QuitRunLoop(const base::WeakPtr<MessageLoop::RunLoop>& run_loop);
+
+base::Closure QuitRunLoopClosure(
+    const base::WeakPtr<MessageLoop::RunLoop>& run_loop);
+
 // Turns on nestable tasks, runs all pending tasks in the message loop,
 // then resets nestable tasks to what they were originally. Prefer this
 // over MessageLoop::RunAllPending for in process browser tests to run
@@ -301,37 +310,36 @@ bool SendMouseMoveSync(const gfx::Point& location) WARN_UNUSED_RESULT;
 bool SendMouseEventsSync(ui_controls::MouseButton type,
                          int state) WARN_UNUSED_RESULT;
 
-// Run a message loop only for the specified amount of time.
-class TimedMessageLoopRunner {
+// Helper class to Run and Quit the message loop. Run and Quit can only happen
+// once per instance. Make a new instance for each use. Calling Quit after Run
+// has returned is safe and has no effect.
+class MessageLoopRunner
+    : public base::RefCounted<MessageLoopRunner> {
  public:
-  // Create new MessageLoopForUI and attach to it.
-  TimedMessageLoopRunner();
-
-  // Attach to an existing message loop.
-  explicit TimedMessageLoopRunner(MessageLoop* loop)
-      : loop_(loop), owned_(false), quit_loop_invoked_(false) {}
+  MessageLoopRunner();
 
-  ~TimedMessageLoopRunner();
+  // Run the current MessageLoop. This can't be called recursively.
+  void Run();
 
-  // Run the message loop for ms milliseconds.
-  void RunFor(int ms);
+  // Quit the matching call to Run (nested MessageLoops are unaffected).
+  void QuitNow();
 
-  // Post Quit task to the message loop.
-  void Quit();
-
-  // Post delayed Quit task to the message loop.
-  void QuitAfter(int ms);
-
-  bool WasTimedOut() const {
-    return !quit_loop_invoked_;
-  }
+  // Hand this closure off to code that uses callbacks to notify completion.
+  // Example:
+  //   scoped_refptr<MessageLoopRunner> runner =
+  //       new MessageLoopRunner;
+  //   // Must be no nested MessageLoop::Run calls during kick_off_some_api:
+  //   kick_off_some_api(runner.QuitNowClosure());
+  //   runner.Run();
+  base::Closure QuitNowClosure();
 
  private:
-  MessageLoop* loop_;
-  bool owned_;
-  bool quit_loop_invoked_;
+  friend class base::RefCounted<MessageLoopRunner>;
+  ~MessageLoopRunner();
+
+  MessageLoop::RunLoop run_loop_;
 
-  DISALLOW_COPY_AND_ASSIGN(TimedMessageLoopRunner);
+  DISALLOW_COPY_AND_ASSIGN(MessageLoopRunner);
 };
 
 // This is a utility class for running a python websocket server
@@ -446,6 +454,7 @@ class WindowedNotificationObserver : public content::NotificationObserver {
 
   content::NotificationSource source_;
   content::NotificationDetails details_;
+  scoped_refptr<MessageLoopRunner> message_loop_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowedNotificationObserver);
 };
@@ -539,6 +548,7 @@ class TitleWatcher : public content::NotificationObserver {
   content::WebContents* web_contents_;
   std::vector<string16> expected_titles_;
   content::NotificationRegistrar notification_registrar_;
+  scoped_refptr<MessageLoopRunner> message_loop_runner_;
 
   // The most recently observed expected title, if any.
   string16 observed_title_;
@@ -638,6 +648,7 @@ class DOMMessageQueue : public content::NotificationObserver {
   content::NotificationRegistrar registrar_;
   std::queue<std::string> message_queue_;
   bool waiting_for_message_;
+  scoped_refptr<MessageLoopRunner> message_loop_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(DOMMessageQueue);
 };