Remove DownloadController java weak reference

chrome/browser/android/download/download_controller.h

 // Copyright 2016 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.
 
 // This class pairs with DownloadController on Java side to forward requests
 // for GET downloads to the current DownloadListener. POST downloads are
 // handled on the native side.
 //
 // Both classes are Singleton classes. C++ object owns Java object.
 //
@@ skipping 15 matching lines @@
 namespace content {
 class WebContents;
 }
 
 class DownloadController : public DownloadControllerBase {
  public:
   static DownloadController* GetInstance();
 
   static bool RegisterDownloadController(JNIEnv* env);
 
-  // Called when DownloadController Java object is instantiated.
-  void Init(JNIEnv* env, jobject obj);
-
   // DownloadControllerBase implementation.
   void AcquireFileAccessPermission(
       const content::ResourceRequestInfo::WebContentsGetter& wc_getter,
       const AcquireFileAccessPermissionCallback& callback) override;
   void CreateAndroidDownload(
       const content::ResourceRequestInfo::WebContentsGetter& wc_getter,
       const DownloadInfo& info) override;
 
   // UMA histogram enum for download cancellation reasons. Keep this
   // in sync with MobileDownloadCancelReason in histograms.xml. This should be
@@ skipping 11 matching lines @@
     CANCEL_REASON_MAX
   };
   static void RecordDownloadCancelReason(DownloadCancelReason reason);
 
   // Callback when user permission prompt finishes. Args: whether file access
   // permission is acquired, which permission to update.
   typedef base::Callback<void(bool, const std::string&)>
       AcquirePermissionCallback;
 
  private:
-  struct JavaObject;
   friend struct base::DefaultSingletonTraits<DownloadController>;
   DownloadController();
   ~DownloadController() override;
 
   // Helper method for implementing AcquireFileAccessPermission().
   bool HasFileAccessPermission();
 
   // DownloadControllerBase implementation.
   void OnDownloadStarted(content::DownloadItem* download_item) override;
   void StartContextMenuDownload(const content::ContextMenuParams& params,
@@ skipping 11 matching lines @@
       content::WebContents* web_contents);
 
   // Helper methods to start android download on UI thread.
   void StartAndroidDownload(
       const content::ResourceRequestInfo::WebContentsGetter& wc_getter,
       const DownloadInfo& info);
   void StartAndroidDownloadInternal(
       const content::ResourceRequestInfo::WebContentsGetter& wc_getter,
       const DownloadInfo& info, bool allowed);
 
-  // Creates Java object if it is not created already and returns it.
-  JavaObject* GetJavaObject();
-
-  JavaObject* java_object_;
-
   std::string default_file_name_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadController);
 };
 
 #endif  // CHROME_BROWSER_ANDROID_DOWNLOAD_DOWNLOAD_CONTROLLER_H_