Allow cross dependencies between BCKSF and BSKSF

components/keyed_service/ios/browser_state_helper.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_KEYED_SERVICE_IOS_BROWSER_STATE_HELPER_H_
 #define COMPONENTS_KEYED_SERVICE_IOS_BROWSER_STATE_HELPER_H_
 
 namespace base {
 class SupportsUserData;
 }
 
 namespace web {
 class BrowserState;
 }
 
-// TODO(sdefresne): remove this file and all usage of the methods once iOS code
-// only use BrowserStateKeyedServiceFactory, http://crbug.com/419366
+// TODO(ios): remove this file and all usage of the methods once iOS code only
+// use BrowserStateKeyedServiceFactory, http://crbug.com/478763
 
-// |BrowserStateFromContextFn| converts from a base::SupportsUserData as passed
-// to a (Refcounted)?BrowserStateKeyedServiceFactory to a web::BrowserState.
-using BrowserStateFromContextFn =
+// Typedef for a function converting a base::SupportsUserData to the underlying
+// web::BrowserState.
+using UnderlyingContextFromContextFn =
     web::BrowserState* (*)(base::SupportsUserData*);
 
-// Registers an helper function to convert a |context| to a web::BrowserState
-// to allow the embedder to overrides how the BSKSF does the conversion.
-void SetBrowserStateFromContextHelper(BrowserStateFromContextFn helper);
+// Registers an |helper| that allows the embedder to control how the underlying
+// web::BrowserState is obtained from a base::SupportsUserData.
+void SetUnderlyingContextFromContextHelper(
+    UnderlyingContextFromContextFn helper);
 
-// Converts a |context| to a web::BrowserState using the helper registered by
-// the embedder if any. Usage is restricted to //components/keyed_service/ios.
-web::BrowserState* BrowserStateFromContext(base::SupportsUserData* context);
+// Returns the underlying web::BrowserState that corresponds to |context| using
+// the helper registered via SetUnderlyingContextFromContextHelper().
+web::BrowserState* UnderlyingContextFromContext(
+    base::SupportsUserData* context);
+
+// Typedef for a function converting a web::BrowserState to the original
+// base::SupportsUserData.
+using OriginalContextFromContextFn =
+    base::SupportsUserData* (*)(web::BrowserState*);
+
+// Registers an |helper| that allows the embedder to control how the original
+// base::SupportsUserData is obtained from a web::BrowserState.
+void SetOriginalContextFromContextHelper(OriginalContextFromContextFn helper);
+
+// Returns the original base::SupportsUserData that corresponds to |context|
+// using the helper registered via SetOriginalContextFromContextHelper().
+base::SupportsUserData* OriginalContextFromContext(
+    base::SupportsUserData* context);
 
 #endif  // COMPONENTS_KEYED_SERVICE_IOS_BROWSER_STATE_HELPER_H_