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

content/test/test_navigation_observer.cc

 // Copyright (c) 2012 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 "content/public/test/test_navigation_observer.h"
 
 #include "base/bind.h"
 #include "base/message_loop.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
@@ skipping 66 matching lines @@
     return;
 
   EXPECT_FALSE(running_);
   running_ = true;
   done_callback_ = done_callback;
   wait_loop_callback.Run();
   EXPECT_TRUE(done_);
 }
 
 void TestNavigationObserver::Wait() {
+  int message_loop_run_id = MessageLoop::current()->next_run_id();

[jar (doing other things), 2012/06/14 04:50:29]

re: discussion of changing API from next_run_id().

Although I think this code works... this hints at why this next_run_id() API
could be problematic.  The issue is that the call has global impact (it changes
some global?), and hence is not re-entrant.  If any of the calls in lines 88-94
happened to induce nested runs, and need to call next_run_id(), then the value
would be "wrong" by the time it was used in line 94.

I think the API needs to be clearly re-entrant... and should  atomically do the
Run() and establish the ID (rather than doing them separately).

[jbates, 2012/06/15 02:20:38]

Done.

   WaitForObservation(
       base::Bind(&MessageLoop::Run,
                  base::Unretained(MessageLoop::current())),
-      base::Bind(&MessageLoop::Quit,
-                 base::Unretained(MessageLoop::current())));
+      base::Bind(&MessageLoop::PostTask,
+                 base::Unretained(MessageLoop::current()),
+                 FROM_HERE,
+                 MessageLoop::QuitNowByIDClosure(message_loop_run_id)));
 }
 
 TestNavigationObserver::TestNavigationObserver(
     JsInjectionReadyObserver* js_injection_ready_observer,
     int number_of_navigations)
     : navigation_started_(false),
       navigations_completed_(0),
       number_of_navigations_(number_of_navigations),
       js_injection_ready_observer_(js_injection_ready_observer),
       done_(false),
@@ skipping 22 matching lines @@
   switch (type) {
     case NOTIFICATION_NAV_ENTRY_COMMITTED:
     case NOTIFICATION_LOAD_START:
       navigation_started_ = true;
       break;
     case NOTIFICATION_LOAD_STOP:
       if (navigation_started_ &&
           ++navigations_completed_ == number_of_navigations_) {
         navigation_started_ = false;
         done_ = true;
-        if (running_)
+        if (running_) {
+          running_ = false;
           done_callback_.Run();
+        }
       }
       break;
     case NOTIFICATION_RENDER_VIEW_HOST_CREATED:
       rvho_send_js_.reset(new RVHOSendJS(
           Source<RenderViewHost>(source).ptr(),
           js_injection_ready_observer_));
       break;
     default:
       NOTREACHED();
   }
 }
 
 }  // namespace content