Remove most native WebContents references from Java

chrome/browser/prerender/external_prerender_handler_android.h

 // Copyright 2013 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 CHROME_BROWSER_PRERENDER_EXTERNAL_PRERENDER_HANDLER_ANDROID_H_
 #define CHROME_BROWSER_PRERENDER_EXTERNAL_PRERENDER_HANDLER_ANDROID_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
 #include "base/memory/scoped_ptr.h"
 
 class GURL;
 class Profile;
 
 namespace content {
 class WebContents;
 }
 
 namespace prerender {
 class PrerenderHandle;
 
 // A class for handling external prerender requests from other applications.
 class ExternalPrerenderHandlerAndroid {
  public:
-  explicit ExternalPrerenderHandlerAndroid();
+  ExternalPrerenderHandlerAndroid();
 
   // Add a prerender with the given url and referrer on the PrerenderManager of
   // the given profile. This is restricted to a single prerender at a time.
   bool AddPrerender(JNIEnv* env,
                     jobject obj,
                     jobject profile,
-                    jlong web_content_ptr,
+                    jobject jweb_contents,
                     jstring url,
                     jstring referrer,
                     jint width,
                     jint height);
 
   // Cancel the prerender associated with the prerender_handle_
   void CancelCurrentPrerender(JNIEnv* env, jobject object);
 
   // Whether the PrerenderManager associated with the given profile has any
   // prerenders for the url.
   static bool HasPrerenderedUrl(Profile* profile,
                                 GURL url,
                                 content::WebContents* web_contents);
 
   // Whether the cookie store associated with this profile has been loaded.
   static bool HasCookieStoreLoaded(Profile* profile);
 
   static bool RegisterExternalPrerenderHandlerAndroid(JNIEnv* env);
 
  private:
   virtual ~ExternalPrerenderHandlerAndroid();
   scoped_ptr<prerender::PrerenderHandle> prerender_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalPrerenderHandlerAndroid);
 };
 
 } // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_EXTERNAL_PRERENDER_HANDLER_ANDROID_H_