[content] Expose renderer scheduler task queues in content::RenderThread.

content/public/test/mock_render_thread.h

Index: content/public/test/mock_render_thread.h
diff --git a/content/public/test/mock_render_thread.h b/content/public/test/mock_render_thread.h
index 63f492c24b8d375f0538f2b1e698f00d2191997b..67e625df02003d484462b01260cfe8788b808b98 100644
--- a/content/public/test/mock_render_thread.h
+++ b/content/public/test/mock_render_thread.h
@@ -81,6 +81,8 @@ class MockRenderThread : public RenderThread {
   bool ResolveProxy(const GURL& url, std::string* proxy_list) override;
   base::WaitableEvent* GetShutdownEvent() override;
   int32_t GetClientId() override;
+  scoped_refptr<base::SingleThreadTaskRunner> GetTimerTaskRunner() override;
+  scoped_refptr<base::SingleThreadTaskRunner> GetLoadingTaskRunner() override;
 #if defined(OS_WIN)
   void PreCacheFont(const LOGFONT& log_font) override;
   void ReleaseCachedFonts() override;