Clean up Android DownloadManager code as most download now go through Chrome Network stack

chrome/browser/android/download/chrome_download_delegate.h

Index: chrome/browser/android/download/chrome_download_delegate.h
diff --git a/chrome/browser/android/download/chrome_download_delegate.h b/chrome/browser/android/download/chrome_download_delegate.h
index 864be455aca0aa1a43daf82b46d1e03b5a44272c..2fd96f342f171386656ddfea85d6de88e06582d7 100644
--- a/chrome/browser/android/download/chrome_download_delegate.h
+++ b/chrome/browser/android/download/chrome_download_delegate.h
@@ -19,18 +19,7 @@ class ChromeDownloadDelegate
 
   void SetJavaRef(JNIEnv*, jobject obj);
 
-  void RequestHTTPGetDownload(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);
-  void OnDownloadStarted(const std::string& filename,
-                         const std::string& mime_type);
+  void OnDownloadStarted(const std::string& filename);
   void OnDangerousDownload(const std::string& filename,
                            const std::string& guid);
   void RequestFileAccess(intptr_t callback_id);