Add UMA for studying download cancellation reasons

chrome/browser/android/download/chrome_download_manager_overwrite_infobar_delegate.cc

 // 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.
 
 #include "chrome/browser/android/download/chrome_download_manager_overwrite_infobar_delegate.h"
 
 #include <memory>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/files/file_util.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/infobars/infobar_service.h"
 #include "chrome/browser/ui/android/infobars/download_overwrite_infobar.h"
 #include "components/infobars/core/infobar.h"
+#include "content/public/browser/android/download_controller_android.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 
 namespace {
 
 void DeleteExistingDownloadFile(
     const base::FilePath& download_path,
     const DownloadTargetDeterminerDelegate::FileSelectedCallback& callback) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
   base::File::Info info;
@@ skipping 62 matching lines @@
   return suggested_download_path_.DirName().BaseName().value();
 }
 
 std::string ChromeDownloadManagerOverwriteInfoBarDelegate::GetDirFullPath()
     const {
   return suggested_download_path_.DirName().value();
 }
 
 void ChromeDownloadManagerOverwriteInfoBarDelegate::InfoBarDismissed() {
   file_selected_callback_.Run(base::FilePath());
+  content::DownloadControllerAndroid::RecordDownloadCancelReason(
+      content::DownloadControllerAndroid::kOverwriteInfobarDismissed);
 }
 
 void ChromeDownloadManagerOverwriteInfoBarDelegate::CreateNewFileInternal(
     const base::FilePath& suggested_download_path,
     const DownloadTargetDeterminerDelegate::FileSelectedCallback& callback) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
   int uniquifier = base::GetUniquePathNumber(suggested_download_path,
                                              base::FilePath::StringType());
   base::FilePath new_path = suggested_download_path;
   if (uniquifier > 0) {
     new_path = suggested_download_path.InsertBeforeExtensionASCII(
         base::StringPrintf(" (%d)", uniquifier));
   }
   content::BrowserThread::PostTask(content::BrowserThread::UI, FROM_HERE,
                                    base::Bind(callback, new_path));
 }
 
 }  // namespace android
 }  // namespace chrome