Count external PDF viewer usage in print preview.

BUG=393024

Review URL: https://codereview.chromium.org/384983002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@282516 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/webui/print_preview/print_preview_handler.cc

@@ -118,6 +118,7 @@ enum PrintSettingsBuckets {
   HEADERS_AND_FOOTERS,
   CSS_BACKGROUND,
   SELECTION_ONLY,
+  EXTERNAL_PDF_PREVIEW,
   PRINT_SETTINGS_BUCKET_BOUNDARY
 };
 
@@ -261,6 +262,12 @@ void ReportPrintSettingsStats(const base::DictionaryValue& settings) {
                           &selection_only) && selection_only) {
     ReportPrintSettingHistogram(SELECTION_ONLY);
   }
+
+  bool external_preview = false;
+  if (settings.GetBoolean(printing::kSettingOpenPDFInPreview,
+                          &external_preview) && external_preview) {
+    ReportPrintSettingHistogram(EXTERNAL_PDF_PREVIEW);
+  }
 }
 
 // Callback that stores a PDF file on disk.

tools/metrics/histograms/histograms.xml

@@ -44668,6 +44668,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="8" label="HEADERS_AND_FOOTERS"/>
   <int value="9" label="CSS_BACKGROUND"/>
   <int value="10" label="SELECTION_ONLY"/>
+  <int value="11" label="EXTERNAL_PDF_PREVIEW"/>
 </enum>
 
 <enum name="PrivetNotificationsEvent" type="int">