Move DownloadControllerAndroid from content/ to chrome/

chrome/browser/android/download/chrome_download_delegate.h

 // Copyright 2015 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_ANDROID_DOWNLOAD_CHROME_DOWNLOAD_DELEGATE_H_
 #define CHROME_BROWSER_ANDROID_DOWNLOAD_CHROME_DOWNLOAD_DELEGATE_H_
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_weak_ref.h"
 #include "base/android/scoped_java_ref.h"
+#include "content/public/browser/android/download_delegate.h"
 
-class ChromeDownloadDelegate {
+class ChromeDownloadDelegate : public content::DownloadDelegate {
  public:
   // Returns true iff this request resulted in the tab creating the download
   // to close.
   static bool EnqueueDownloadManagerRequest(jobject chrome_download_delegate,
                                             bool overwrite,
                                             jobject download_info);
+  ChromeDownloadDelegate(jobject obj);
+
+  // DownloadDelegate implementation
+  void NewHTTPGetDownload(const std::string& url,
+                          const std::string& user_agent,
+                          const std::string& content_disposition,
+                          const std::string& mime_type,
+                          const std::string& cookie,
+                          const std::string& referer,
+                          const base::string16& file_name,
+                          int64_t content_length,
+                          bool has_user_geature,
+                          bool must_download) override;
+  void OnDownloadStarted(const std::string& filename,
+                         const std::string& mime_type);
+  void OnDangerousDownload(const std::string& filename,
+                           const std::string& guid);
+  void RequestFileAccess(intptr_t callback_id);
+
+ private:
+  base::android::ScopedJavaGlobalRef<jobject> obj_;

[no sievers, 2016/06/02 23:29:06]

If the native instance holds a global ref, we have to make sure that the native
instance gets deleted when the Tab tears down, because DownloadController(.java)
holds a back reference to the Tab. Or you might end up with a circular
dependency.

[Jinsuk Kim, 2016/06/03 11:04:14]

Replaced with weak reference to it so that ChromeDownloadDelegate (java) can get
deleted when Tab loads a new WebContents/ContentViewCore. 

 };
 
 bool RegisterChromeDownloadDelegate(JNIEnv* env);
 
 #endif  // CHROME_BROWSER_ANDROID_DOWNLOAD_CHROME_DOWNLOAD_DELEGATE_H_