Cache Storage: Add Platform API to retrieve CacheStorage for origin

public/platform/Platform.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 83 matching lines @@
 class WebPluginListBuilder;
 class WebPrescientNetworking;
 class WebPublicSuffixList;
 class WebPushProvider;
 class WebRTCPeerConnectionHandler;
 class WebRTCPeerConnectionHandlerClient;
 class WebSandboxSupport;
 class WebScheduler;
 class WebSecurityOrigin;
 class WebScrollbarBehavior;
+class WebServiceWorkerCacheStorage;
 class WebSocketHandle;
 class WebSpeechSynthesizer;
 class WebSpeechSynthesizerClient;
 class WebStorageNamespace;
 class WebSyncProvider;
 struct WebFloatPoint;
 class WebThemeEngine;
 class WebThread;
 class WebURL;
 class WebURLLoader;
@@ skipping 98 matching lines @@
 
     virtual WebString convertIDNToUnicode(const WebString& host, const WebString& languages) { return host; }
 
 
     // IndexedDB ----------------------------------------------------------
 
     // Must return non-null.
     virtual WebIDBFactory* idbFactory() { return 0; }
 
 
+    // Cache Storage ----------------------------------------------------------
+
+    // The caller is responsible for deleting the returned object.
+    virtual WebServiceWorkerCacheStorage* cacheStorage(const WebString& originIdentifier) { return nullptr; }
+
     // Gamepad -------------------------------------------------------------
 
     virtual void sampleGamepads(WebGamepads& into) { into.length = 0; }
 
 
     // WebVR -------------------------------------------------------------
 
     virtual void getVRDevices(WebVector<blink::WebVRDevice>* devices) { };
 
     virtual void getHMDSensorState(unsigned index, blink::WebHMDSensorState& into) { }
@@ skipping 460 matching lines @@
 protected:
     BLINK_PLATFORM_EXPORT Platform();
     virtual ~Platform() { }
 
     WebThread* m_mainThread;
 };
 
 } // namespace blink
 
 #endif