Isolate initiation counts for downloads to their own histograms and improve

chrome/browser/download/download_util.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.
 //
 // Download utility implementation
 
 #include "chrome/browser/download/download_util.h"
 
 #if defined(OS_WIN)
 #include <shobjidl.h>
@@ skipping 615 matching lines @@
                               in_progress,
                               kMaxShelfSize);
   }
 }
 
 void RecordDownloadCount(ChromeDownloadCountTypes type) {
   UMA_HISTOGRAM_ENUMERATION(
       "Download.CountsChrome", type, DOWNLOAD_COUNT_TYPES_LAST_ENTRY);
 }
 
+void RecordDownloadSource(ChromeDownloadInitiationSources source) {
+  UMA_HISTOGRAM_ENUMERATION(
+      "Download.SourcesChrome", source, DOWNLOAD_INITIATION_SOURCES_LAST_ENTRY);
+}
+
 }  // namespace download_util