[DevTools] Use InspectorFrontendHost.readyForTest for layout tests.

chrome/browser/devtools/devtools_window_testing.cc

 // Copyright 2014 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 "chrome/browser/devtools/devtools_window_testing.h"
 
 #include "base/lazy_instance.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/devtools/devtools_window.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 78 matching lines @@
 
 // static
 void DevToolsWindowTesting::WindowClosed(DevToolsWindow* window) {
   DevToolsWindowTesting* testing = DevToolsWindowTesting::Find(window);
   if (testing)
     delete testing;
 }
 
 // static
 void DevToolsWindowTesting::WaitForDevToolsWindowLoad(DevToolsWindow* window) {
-  scoped_refptr<content::MessageLoopRunner> runner =
-      new content::MessageLoopRunner;
-  window->ready_for_test_callback_ = runner->QuitClosure();
-  runner->Run();
+  if (!window->ready_for_test_) {
+    scoped_refptr<content::MessageLoopRunner> runner =
+        new content::MessageLoopRunner;
+    window->ready_for_test_callback_ = runner->QuitClosure();
+    runner->Run();
+  }
   base::string16 harness = base::UTF8ToUTF16(
       content::DevToolsFrontendHost::GetFrontendResource(kHarnessScript));
   window->main_web_contents_->GetMainFrame()->ExecuteJavaScript(harness);
 }
 
 // static
 DevToolsWindow* DevToolsWindowTesting::OpenDevToolsWindowSync(
     content::WebContents* inspected_web_contents,
     bool is_docked) {
   std::string settings = is_docked ?
@@ skipping 85 matching lines @@
   if (!devtools_windows_.size())
     return nullptr;
   return devtools_windows_[devtools_windows_.size() - 1];
 }
 
 void DevToolsWindowCreationObserver::CloseAllSync() {
   for (DevToolsWindow* window : devtools_windows_)
     DevToolsWindowTesting::CloseDevToolsWindowSync(window);
   devtools_windows_.clear();
 }