Destroy the old RenderWidgetHostView when swapping out a main frame.

content/public/test/test_renderer_host.h

Index: content/public/test/test_renderer_host.h
diff --git a/content/public/test/test_renderer_host.h b/content/public/test/test_renderer_host.h
index b9d04a20acb5d58023e334b005d496ceeececd9f..18fd37aaf25560fea6ff003867ce857673517192 100644
--- a/content/public/test/test_renderer_host.h
+++ b/content/public/test/test_renderer_host.h
@@ -175,10 +175,17 @@ class RenderViewHostTestEnabler {
   RenderViewHostTestEnabler();
   ~RenderViewHostTestEnabler();
 
+  void SetUp();

[Charlie Reis, 2016/11/29 19:35:55]

This needs a comment.  Lots of classes instantiate one of these (e.g.,
ExtensionEventObserverTest), but it doesn't look like you call SetUp in all of
them?  Why not?

+  void TearDown();
+
  private:
   DISALLOW_COPY_AND_ASSIGN(RenderViewHostTestEnabler);
   friend class RenderViewHostTestHarness;
 
+#if defined(OS_ANDROID)
+  std::unique_ptr<MockGpuChannelEstablishFactory> gpu_channel_factory_;
+  std::unique_ptr<display::Screen> screen_;
+#endif
   std::unique_ptr<MockRenderProcessHostFactory> rph_factory_;
   std::unique_ptr<TestRenderViewHostFactory> rvh_factory_;
   std::unique_ptr<TestRenderFrameHostFactory> rfh_factory_;
@@ -280,10 +287,6 @@ class RenderViewHostTestHarness : public testing::Test {
 #if defined(USE_AURA)
   std::unique_ptr<aura::test::AuraTestHelper> aura_test_helper_;
 #endif
-#if defined(OS_ANDROID)
-  std::unique_ptr<MockGpuChannelEstablishFactory> gpu_channel_factory_;
-  std::unique_ptr<display::Screen> screen_;
-#endif
   RenderViewHostTestEnabler rvh_test_enabler_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderViewHostTestHarness);