[XHR] Use hasPendingActivity() to manage XHR's life time.

Source/core/xml/XMLHttpRequest.h

Index: Source/core/xml/XMLHttpRequest.h
diff --git a/Source/core/xml/XMLHttpRequest.h b/Source/core/xml/XMLHttpRequest.h
index dfb585e3504e66a475c303ff0bcd54d095651ba2..d04e438a454c553d1ac916cee433c100d22d0db6 100644
--- a/Source/core/xml/XMLHttpRequest.h
+++ b/Source/core/xml/XMLHttpRequest.h
@@ -30,7 +30,6 @@
 #include "core/loader/ThreadableLoaderClient.h"
 #include "core/xml/XMLHttpRequestEventTarget.h"
 #include "core/xml/XMLHttpRequestProgressEventThrottle.h"
-#include "platform/AsyncMethodRunner.h"
 #include "platform/network/FormData.h"
 #include "platform/network/ResourceResponse.h"
 #include "platform/weborigin/SecurityOrigin.h"
@@ -79,15 +78,14 @@ public:
         ResponseTypeStream
     };
 
-    enum DropProtection {
-        DropProtectionSync,
-        DropProtectionAsync,
-    };
-
-    virtual void contextDestroyed();
-    virtual void suspend();
-    virtual void resume();
-    virtual void stop();
+    // ActiveDOMObject implementaions
+    virtual void contextDestroyed() OVERRIDE;
+    // Keep the JavaScript wrapper alive while a request is in progress so that
+    // this object (which is a listener for m_loader) is also kept alive.
+    virtual bool hasPendingActivity() const OVERRIDE;
+    virtual void suspend() OVERRIDE;
+    virtual void resume() OVERRIDE;
+    virtual void stop() OVERRIDE;
 
     virtual const AtomicString& interfaceName() const OVERRIDE;
     virtual ExecutionContext* executionContext() const OVERRIDE;
@@ -172,12 +170,10 @@ private:
     void changeState(State newState);
     void dispatchReadyStateChangeEvent();
 
-    void dropProtectionSoon();
-    void dropProtection();
     // Clears variables used only while the resource is being loaded.
     void clearVariablesForLoading();
     // Returns false iff reentry happened and a new load is started.
-    bool internalAbort(DropProtection = DropProtectionSync);
+    bool internalAbort();
     // Clears variables holding response header and body data.
     void clearResponse();
     void clearRequest();
@@ -256,7 +252,6 @@ private:
 
     // An enum corresponding to the allowed string values for the responseType attribute.
     ResponseTypeCode m_responseTypeCode;
-    AsyncMethodRunner<XMLHttpRequest> m_dropProtectionRunner;
     RefPtr<SecurityOrigin> m_securityOrigin;
 };