Track frame openers in FrameTreeNodes instead of WebContents

content/test/test_web_contents.h

Index: content/test/test_web_contents.h
diff --git a/content/test/test_web_contents.h b/content/test/test_web_contents.h
index de3a10353bcde6289bd32cd1baf22e7ed2cdca72..b94aed63cd2737cc0042f9a6df2baa96cb4643eb 100644
--- a/content/test/test_web_contents.h
+++ b/content/test/test_web_contents.h
@@ -79,7 +79,8 @@ class TestWebContents : public WebContentsImpl, public WebContentsTester {
     delegate_view_override_ = view;
   }
 
-  // Allows us to simulate this tab having an opener.
+  // Allows us to simulate this tab's main frame having an opener that points
+  // to the main frame of the |opener|.
   void SetOpener(TestWebContents* opener);
 
   // Allows us to simulate that a contents was created via CreateNewWindow.