Add font substitution metric for Linux

pdf/out_of_process_instance.cc

Index: pdf/out_of_process_instance.cc
diff --git a/pdf/out_of_process_instance.cc b/pdf/out_of_process_instance.cc
index 92511185c9715dd610adc6353cae440616666284..512212130fb018fd1318ed1ee6237f99cd168cf1 100644
--- a/pdf/out_of_process_instance.cc
+++ b/pdf/out_of_process_instance.cc
@@ -282,6 +282,7 @@ OutOfProcessInstance::OutOfProcessInstance(PP_Instance instance)
       preview_document_load_state_(LOAD_STATE_COMPLETE),
       uma_(this),
       told_browser_about_unsupported_feature_(false),
+      font_substitution_reported_(false),
       print_preview_page_count_(0),
       last_progress_sent_(0),
       recently_sent_find_update_(false),
@@ -1206,6 +1207,10 @@ void OutOfProcessInstance::DocumentLoadComplete(int page_count) {
   UserMetricsRecordAction("PDF.LoadSuccess");
   uma_.HistogramEnumeration("PDF.DocumentFeature", LOADED_DOCUMENT,
                             FEATURES_COUNT);
+#if defined(OS_LINUX)
+  if (!font_substitution_reported_)
+    uma_.HistogramEnumeration("PDF.IsFontSubstituted", 0, 2);
+#endif
 
   // Note: If we are in print preview mode the scroll location is retained
   // across document loads so we don't want to scroll again and override it.
@@ -1312,6 +1317,13 @@ void OutOfProcessInstance::DocumentLoadFailed() {
   PostMessage(message);
 }
 
+void OutOfProcessInstance::FontSubstituted() {
+  if (font_substitution_reported_)

[Lei Zhang, 2016/10/12 18:56:38]

Can we have a matching #if defined() here? Also for
|font_substitution_reported_| as well. Maybe if the build tools see an empty
virtual function, they will be smart enough to optimize it away.

+    return;
+  font_substitution_reported_ = true;
+  uma_.HistogramEnumeration("PDF.IsFontSubstituted", 1, 2);
+}
+
 void OutOfProcessInstance::PreviewDocumentLoadFailed() {
   UserMetricsRecordAction("PDF.PreviewDocumentLoadFailure");
   if (preview_document_load_state_ != LOAD_STATE_LOADING ||