Add error description to the DidFailProvisionalLoad callback.

content/renderer/mock_content_renderer_client.cc

Index: content/renderer/mock_content_renderer_client.cc
diff --git a/content/renderer/mock_content_renderer_client.cc b/content/renderer/mock_content_renderer_client.cc
index eef79817ec9ec19e307147ab9b48a4ff40ecfe93..984afa905ec01b30bb04a1da3ea1950c39383d59 100644
--- a/content/renderer/mock_content_renderer_client.cc
+++ b/content/renderer/mock_content_renderer_client.cc
@@ -42,10 +42,11 @@ bool MockContentRendererClient::HasErrorPage(int http_status_code,
   return false;
 }
 
-std::string MockContentRendererClient::GetNavigationErrorHtml(
+void MockContentRendererClient::GetNavigationErrorStrings(
     const WebKit::WebURLRequest& failed_request,
-    const WebKit::WebURLError& error) {
-  return std::string();
+    const WebKit::WebURLError& error,
+    std::string* error_html,
+    string16* error_description) {
 }
 
 bool MockContentRendererClient::RunIdleHandlerWhenWidgetsHidden() {