Add an ability to call WebKit's WebFrame::loadData via NavigationController.

content/public/browser/navigation_controller.h

Index: content/public/browser/navigation_controller.h
diff --git a/content/public/browser/navigation_controller.h b/content/public/browser/navigation_controller.h
index c9c1a01384a76cd56736af5fe1bc2e9e5c4ec4fd..0973884ffdd917296cff2639f65809ff5cf1032e 100644
--- a/content/public/browser/navigation_controller.h
+++ b/content/public/browser/navigation_controller.h
@@ -167,6 +167,14 @@ class NavigationController {
                                    PageTransition type,
                                    const std::string& extra_headers) = 0;
 
+  // Loads a 'data:' scheme URL with specified base URL and a history entry URL.
+  // This can only be used for browser-initiated navigations.

[Charlie Reis, 2012/06/19 17:17:25]

Thanks.  Now that I know a bit more, I think we need to provide a stronger
warning here.  Something like "This is only safe to be used for
browser-initiated data: URL navigations, since it shows arbitrary content as if
it comes from |history_url|."

[mnaganov (inactive), 2012/07/03 08:07:52]

Done. Sorry, I was swamped by other tasks, now I'm returning back to this issue.

+  virtual void LoadDataWithBaseURL(const GURL& data_url,
+                                   const Referrer& referrer,
+                                   const GURL& base_url,
+                                   const GURL& history_url,
+                                   bool is_overriding_user_agent) = 0;
+
   // Behaves like LoadURL() and LoadURLFromRenderer() but marks the new
   // navigation as being transferred from one RVH to another. In this case the
   // browser can recycle the old request once the new renderer wants to