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 d21875cc1db0d7fe1a88ee86ad442f037dfe71a9..03ef615b6c522ec0dc79de6d8445179684820d33 100644
--- a/chrome/test/base/ui_test_utils.h
+++ b/chrome/test/base/ui_test_utils.h
@@ -100,6 +100,18 @@ enum BrowserTestWaitFlags {
 // process browser tests that need to block until a condition is met.
 void RunMessageLoop();
 
+// Variant of RunMessageLoop that takes a |run_id| (from
+// MessageLoop::current()->GetRunID()).
+void RunMessageLoopWithID(const MessageLoop::RunID& run_id);
+
+// Quit the MessageLoop Run of the specified |run_id|.
+void QuitMessageLoopWithID(const MessageLoop::RunID& run_id);
+
+// Get a MessageLoop::QuitNowWithID task that will repost itself a few times to
+// allow the MessageLoop to finish pending tasks (and tasks posted by those
+// pending tasks...).
+base::Closure QuitMessageLoopWithIDClosure(const MessageLoop::RunID& run_id);
+
 // 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
@@ -313,37 +325,39 @@ 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) {}
-
-  ~TimedMessageLoopRunner();
+  MessageLoopRunner();
 
-  // Run the message loop for ms milliseconds.
-  void RunFor(int ms);
+  // Run the current MessageLoop. This can't be called recursively.
+  void Run();
 
-  // Post Quit task to the message loop.
-  void Quit();
+  // Quit the matching call to Run (nested MessageLoops are unaffected).
+  void QuitNow();
 
-  // 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::RunID message_loop_run_id_;
+  bool run_called_;
+  bool quit_received_;
+  bool running_;
 
-  DISALLOW_COPY_AND_ASSIGN(TimedMessageLoopRunner);
+  DISALLOW_COPY_AND_ASSIGN(MessageLoopRunner);
 };
 
 // This is a utility class for running a python websocket server
@@ -458,6 +472,7 @@ class WindowedNotificationObserver : public content::NotificationObserver {
 
   content::NotificationSource source_;
   content::NotificationDetails details_;
+  scoped_refptr<MessageLoopRunner> message_loop_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowedNotificationObserver);
 };
@@ -551,6 +566,7 @@ 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_;
@@ -650,6 +666,7 @@ 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);
 };