(Re-)introduce AncestorThrottle to handle 'X-Frame-Options'.

chrome/renderer/chrome_content_renderer_client.cc

Index: chrome/renderer/chrome_content_renderer_client.cc
diff --git a/chrome/renderer/chrome_content_renderer_client.cc b/chrome/renderer/chrome_content_renderer_client.cc
index 31595060204c0f3718b0db713a8fd699b5e872e2..db5f17f311a1e8d308c40c7ba518935ad675660f 100644
--- a/chrome/renderer/chrome_content_renderer_client.cc
+++ b/chrome/renderer/chrome_content_renderer_client.cc
@@ -1014,6 +1014,22 @@ bool ChromeContentRendererClient::ShouldSuppressErrorPage(
       NetErrorHelper::Get(render_frame)->ShouldSuppressErrorPage(url)) {
     return true;
   }
+
+#if defined(ENABLE_EXTENSIONS)
+  // Suppress error pages for the webstore when it's loaded in a frame. This
+  // mitigates confusion which could arise from the fact that error pages commit
+  // with the same URL as the failed load. Since pieces of the browser sometimes
+  // rely on the last-committed URL as a permission check of sorts, and the
+  // webstore is a special flower, this can cause problems that we can avoid by
+  // simply suppressing the error page (see https://crbug.com/622385, for
+  // example).
+  GURL webstore_url(extension_urls::GetWebstoreLaunchURL());
+  if (!render_frame->IsMainFrame() && url.SchemeIsHTTPOrHTTPS() &&
+      url.DomainIs(webstore_url.host().c_str())) {
+    return true;
+  }
+#endif
+
   // Do not flash an error page if the Instant new tab page fails to load.
   return SearchBouncer::GetInstance()->IsNewTabPage(url);
 }