Record the parallel download UMA for fresh new downloads

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 1247 matching lines @@
     hash_.clear();
     deferred_interrupt_reason_ = new_create_info.result;
     received_slices_.clear();
     TransitionTo(INTERRUPTED_TARGET_PENDING_INTERNAL);
     DetermineDownloadTarget();
     return;
   }
 
   if (state_ == INITIAL_INTERNAL) {
     RecordDownloadCount(NEW_DOWNLOAD_COUNT);
+    if (job_->UsesParallelRequests())
+      RecordParallelDownloadCount(NEW_DOWNLOAD_COUNT);
     RecordDownloadMimeType(mime_type_);
     if (!GetBrowserContext()->IsOffTheRecord()) {
       RecordDownloadCount(NEW_DOWNLOAD_COUNT_NORMAL_PROFILE);
       RecordDownloadMimeTypeForNormalProfile(mime_type_);
     }
   }
 
   // Successful download start.
   DCHECK(download_file_);
   DCHECK(job_);
 
   if (state_ == RESUMING_INTERNAL)
     UpdateValidatorsOnResumption(new_create_info);
 
   if (state_ == INITIAL_INTERNAL && job_->UsesParallelRequests())

[xingliu, 2017/04/12 21:37:39]

Should we remove the state_ check here?

Since it seems START_COUNT and NEW_DOWNLOAD_COUNT are recording the same number.
Maybe START_COUNT is also for resumption.

[qinmin, 2017/04/12 22:32:55]

Yes, we should, since NEW_DOWNLOAD_COUNT enum is added, we should make this the
same when recording download resumption/starts.

     RecordParallelDownloadCount(START_COUNT);
 
   TransitionTo(TARGET_PENDING_INTERNAL);
 
   job_->Start();
 }
 
 void DownloadItemImpl::StartDownload() {
   BrowserThread::PostTask(
       BrowserThread::FILE, FROM_HERE,
@@ skipping 953 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