Have AppCache code go through the content embedder API for content settings checks.

content/browser/content_browser_client.h

Index: content/browser/content_browser_client.h
===================================================================
--- content/browser/content_browser_client.h	(revision 84527)
+++ content/browser/content_browser_client.h	(working copy)
@@ -20,6 +20,7 @@
 
 namespace content {
 
+class ResourceContext;
 class WebUIFactory;
 
 // Embedder API for participating in browser logic.
@@ -61,6 +62,11 @@
   // Returns the locale used by the application.
   virtual std::string GetApplicationLocale();
 
+  // Allow the embedder to control if an AppCache can be used for the given url.
+  // This is called on the IO thread.
+  virtual bool AllowAppCache(const GURL& manifest_url,
+                             const content::ResourceContext* context);
+
 #if defined(OS_LINUX)
   // Can return an optional fd for crash handling, otherwise returns -1.
   virtual int GetCrashSignalFD(const std::string& process_type);