Add UMA for estimating disk bandwidth and the time saved with parallel download

content/browser/download/download_item_impl.cc

 // Copyright (c) 2012 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.
 
 // File method ordering: Methods in this file are in the same order as
 // in download_item_impl.h, with the following exception: The public
 // interface Start is placed in chronological order with the other
 // (private) routines that together define a DownloadItem's state
 // transitions as the download progresses.  See "Download progression
 // cascade" later in this file.
@@ skipping 360 matching lines @@
       // |DownloadJob::is_paused_| even if there's no request currently
       // associated with this DII. When a request is assigned (due to a
       // resumption, for example) we can honor the |DownloadJob::is_paused_|
       // setting.
       return;
 
     case IN_PROGRESS_INTERNAL:
     case TARGET_PENDING_INTERNAL:
       job_->Pause();
       UpdateObservers();
+      if (download_file_) {
+        BrowserThread::PostTask(
+            BrowserThread::FILE, FROM_HERE,
+            base::Bind(&DownloadFile::WasPaused,
+                       // Safe because we control download file lifetime.
+                       base::Unretained(download_file_.get())));
+      }
       return;
 
     case MAX_DOWNLOAD_INTERNAL_STATE:
     case TARGET_RESOLVED_INTERNAL:
       NOTREACHED();
   }
 }
 
 void DownloadItemImpl::Resume() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
@@ skipping 1774 matching lines @@
     case RESUME_MODE_USER_CONTINUE:
       return "USER_CONTINUE";
     case RESUME_MODE_USER_RESTART:
       return "USER_RESTART";
   }
   NOTREACHED() << "Unknown resume mode " << mode;
   return "unknown";
 }
 
 }  // namespace content