Add UMA for studying download cancellation reasons

chrome/browser/android/download/download_manager_service.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_DOWNLOAD_MANAGER_SERVICE_H_
 #define CHROME_BROWSER_ANDROID_DOWNLOAD_DOWNLOAD_MANAGER_SERVICE_H_
 
 #include <jni.h>
 #include <map>
 #include <string>
@@ skipping 25 matching lines @@
   // |jdownload_guid|..
   void ResumeDownload(JNIEnv* env,
                       jobject obj,
                       const JavaParamRef<jstring>& jdownload_guid);
 
   // Called to cancel a download item that has GUID equal to |jdownload_guid|.
   // If the DownloadItem is not yet created, retry after a while.
   void CancelDownload(JNIEnv* env,
                       jobject obj,
                       const JavaParamRef<jstring>& jdownload_guid,
-                      bool is_off_the_record);
+                      bool is_off_the_record,
+                      bool is_notification_dismissed);
 
   // Called to pause a download item that has GUID equal to |jdownload_guid|.
   // If the DownloadItem is not yet created, do nothing as it is already paused.
   void PauseDownload(JNIEnv* env,
                      jobject obj,
                      const JavaParamRef<jstring>& jdownload_guid);
 
   // DownloadHistory::Observer methods.
   void OnHistoryQueryComplete() override;
 
@@ skipping 37 matching lines @@
 
   void EnqueueDownloadAction(const std::string& download_guid,
                              DownloadAction action);
 
   ResumeCallback resume_callback_for_testing_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadManagerService);
 };
 
 #endif  // CHROME_BROWSER_ANDROID_DOWNLOAD_DOWNLOAD_MANAGER_SERVICE_H_