ServiceWorker: add ServiceWorkerClients.claim() support (1/3).

Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.h

Index: Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.h
diff --git a/Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.h b/Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.h
index 1ee2e29a07f61fad98f99e85fc1db0e4f48a1e9d..3c51e4c4ab7dd69500af1ef2d8e1eed0e611b467 100644
--- a/Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.h
+++ b/Source/modules/serviceworkers/ServiceWorkerGlobalScopeClient.h
@@ -35,6 +35,7 @@
 #include "core/workers/WorkerClients.h"
 #include "public/platform/WebMessagePortChannel.h"
 #include "public/platform/WebServiceWorkerClientFocusCallback.h"
+#include "public/platform/WebServiceWorkerClientsClaimCallbacks.h"
 #include "public/platform/WebServiceWorkerClientsInfo.h"
 #include "public/platform/WebServiceWorkerEventResult.h"
 #include "public/platform/WebServiceWorkerSkipWaitingCallbacks.h"
@@ -73,6 +74,7 @@ public:
     virtual void postMessageToClient(int clientID, const WebString& message, PassOwnPtr<WebMessagePortChannelArray>) = 0;
     virtual void postMessageToCrossOriginClient(const WebCrossOriginServiceWorkerClient&, const WebString& message, PassOwnPtr<WebMessagePortChannelArray>) = 0;
     virtual void skipWaiting(WebServiceWorkerSkipWaitingCallbacks*) = 0;
+    virtual void claim(WebServiceWorkerClientsClaimCallbacks*) = 0;
     virtual void focus(int clientID, WebServiceWorkerClientFocusCallback*) = 0;
 
     static const char* supplementName();