Adds test for out-of-process iframes with display:none.

This test verifies that blink::WebRemoteFrameImpl::isIgnoredForHitTest
doesn't crash the renderer when a RemoteFrame is set to display:none.

BUG=582149

Review URL: https://codereview.chromium.org/1654273005

Cr-Commit-Position: refs/heads/master@{#373284}
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index 9197d97..3f083e7 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -553,6 +553,9 @@
   scoped_ptr<WebGraphicsContext3DCommandBufferImpl> CreateGraphicsContext3D(
       GpuChannelHost* gpu_channel_host);
 
+  // Sends an ACK to the browser process during the next compositor frame.
+  void OnWaitNextFrameForTests(int routing_id);
+
   // Routing ID that allows us to communicate to the parent browser process
   // RenderWidgetHost. When MSG_ROUTING_NONE, no messages may be sent.
   int32_t routing_id_;