Add testRunner.runIdleTasks() to force idle tasks to run.

content/shell/renderer/layout_test/blink_test_runner.h

 // 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.
 
 #ifndef CONTENT_SHELL_RENDERER_LAYOUT_TEST_BLINK_TEST_RUNNER_H_
 #define CONTENT_SHELL_RENDERER_LAYOUT_TEST_BLINK_TEST_RUNNER_H_
 
 #include <deque>
 #include <memory>
 #include <vector>
@@ skipping 137 matching lines @@
       blink::WebMediaStream* stream) override;
   cc::SharedBitmapManager* GetSharedBitmapManager() override;
   void DispatchBeforeInstallPromptEvent(
       int request_id,
       const std::vector<std::string>& event_platforms,
       const base::Callback<void(bool)>& callback) override;
   blink::WebPlugin* CreatePluginPlaceholder(
     blink::WebLocalFrame* frame,
     const blink::WebPluginParams& params) override;
   float GetDeviceScaleFactorForTest() const override;
+  void RunIdleTasks(const base::Closure& callback) override;
 
   // Resets a RenderView to a known state for layout tests. It is used both when
   // a RenderView is created and when reusing an existing RenderView for the
   // next test case.
   // When reusing an existing RenderView, |for_new_test| should be true, which
   // also resets additional state, like the main frame's name and opener.
   void Reset(bool for_new_test);
 
   void set_proxy(test_runner::WebTestProxyBase* proxy) { proxy_ = proxy; }
   test_runner::WebTestProxyBase* proxy() const { return proxy_; }
@@ skipping 48 matching lines @@
   bool focus_on_next_commit_;
 
   std::unique_ptr<LeakDetector> leak_detector_;
 
   DISALLOW_COPY_AND_ASSIGN(BlinkTestRunner);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_SHELL_RENDERER_LAYOUT_TEST_BLINK_TEST_RUNNER_H_