Fix a null AppCacheBackendImpl ptr crash in CompleteCrossSiteTransfer and re…

content/browser/appcache/appcache_request_handler.h

Index: content/browser/appcache/appcache_request_handler.h
diff --git a/content/browser/appcache/appcache_request_handler.h b/content/browser/appcache/appcache_request_handler.h
index d7b55e5a96b7feef7906d077785705d3b13e075d..7665d10e0b88cb56eb87e2f9c116d97219492199 100644
--- a/content/browser/appcache/appcache_request_handler.h
+++ b/content/browser/appcache/appcache_request_handler.h
@@ -25,6 +25,7 @@ class URLRequestJob;
 
 namespace content {
 class AppCacheRequestHandlerTest;
+class AppCacheService;
 class AppCacheURLRequestJob;
 
 // An instance is created for each net::URLRequest. The instance survives all
@@ -58,6 +59,12 @@ class CONTENT_EXPORT AppCacheRequestHandler
   void CompleteCrossSiteTransfer(int new_process_id, int new_host_id);
   void MaybeCompleteCrossSiteTransferInOldProcess(int old_process_id);
 
+  // Useful for detecting storage partition mismatches in the context
+  // of cross site transfer navigations.
+  bool SanityCheckIsSameService(AppCacheService* service) {
+    return !host_ || (host_->service() == service);
+  }
+
   static bool IsMainResourceType(ResourceType type) {
     return IsResourceTypeFrame(type) ||
            type == RESOURCE_TYPE_SHARED_WORKER;