Add an error page for resources blocked via XSS Auditor.

Currently, when the XSS Auditor blocks a page, we render a lovely white
rectangle for the user. This, though calming and serene, is not terribly
informative.

This patch wires XSS Auditor blocks up to the general error page
mechanism, giving users some clue as to what's going on.

BUG=654794

Review-Url: https://codereview.chromium.org/2425663002
Cr-Commit-Position: refs/heads/master@{#434375}
diff --git a/content/renderer/render_frame_impl.h b/content/renderer/render_frame_impl.h
index 50be34c..9ef5208 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -511,6 +511,7 @@
                          blink::WebNavigationPolicy policy,
                          const blink::WebString& suggested_name,
                          bool should_replace_current_entry) override;
+  void loadErrorPage(int reason) override;
   blink::WebNavigationPolicy decidePolicyForNavigation(
       const NavigationPolicyInfo& info) override;
   blink::WebHistoryItem historyItemForNewChildFrame() override;