Ensure the 1993 NTP logs to UMA Most Visited tiles that use the fallback thumbnail instead of the p…

chrome/browser/ui/webui/ntp/ntp_user_data_logger.cc

Index: chrome/browser/ui/webui/ntp/ntp_user_data_logger.cc
diff --git a/chrome/browser/ui/webui/ntp/ntp_user_data_logger.cc b/chrome/browser/ui/webui/ntp/ntp_user_data_logger.cc
index 95d86ed2b587601324347e38b26d35404e244337..f3383de159aab38f2b5fc5c267ad8870aa20c2ac 100644
--- a/chrome/browser/ui/webui/ntp/ntp_user_data_logger.cc
+++ b/chrome/browser/ui/webui/ntp/ntp_user_data_logger.cc
@@ -16,12 +16,23 @@ NTPUserDataLogger::~NTPUserDataLogger() {}
 void NTPUserDataLogger::EmitThumbnailErrorRate() {
   DCHECK_LE(number_of_thumbnail_errors_, number_of_thumbnail_attempts_);
   if (number_of_thumbnail_attempts_ != 0) {
-    UMA_HISTOGRAM_PERCENTAGE("NewTabPage.ThumbnailErrorRate",
-                             GetPercentError(number_of_thumbnail_errors_,
-                                             number_of_thumbnail_attempts_));
+    UMA_HISTOGRAM_PERCENTAGE(
+      "NewTabPage.ThumbnailErrorRate",
+      GetPercentError(number_of_thumbnail_errors_,
+                      number_of_thumbnail_attempts_));
+  }
+  DCHECK_LE(number_of_fallback_thumbnails_used_,
+            number_of_fallback_thumbnails_requested_);
+  if (number_of_fallback_thumbnails_requested_ != 0) {
+    UMA_HISTOGRAM_PERCENTAGE(
+        "NewTabPage.ThumbnailFallbackRate",
+        GetPercentError(number_of_fallback_thumbnails_used_,
+                        number_of_fallback_thumbnails_requested_));
   }
   number_of_thumbnail_attempts_ = 0;
   number_of_thumbnail_errors_ = 0;
+  number_of_fallback_thumbnails_requested_ = 0;
+  number_of_fallback_thumbnails_used_ = 0;
 }
 
 void NTPUserDataLogger::EmitMouseoverCount() {
@@ -40,6 +51,12 @@ void NTPUserDataLogger::LogEvent(NTPLoggingEventType event) {
     case NTP_THUMBNAIL_ERROR:
       number_of_thumbnail_errors_++;
       break;
+    case NTP_FALLBACK_THUMBNAIL_REQUESTED:
+      number_of_fallback_thumbnails_requested_++;
+      break;
+    case NTP_FALLBACK_THUMBNAIL_USED:
+      number_of_fallback_thumbnails_used_++;
+      break;
     default:
       NOTREACHED();
   }
@@ -64,7 +81,9 @@ NTPUserDataLogger::NTPUserDataLogger(content::WebContents* contents)
     : content::WebContentsObserver(contents),
       number_of_mouseovers_(0),
       number_of_thumbnail_attempts_(0),
-      number_of_thumbnail_errors_(0) {
+      number_of_thumbnail_errors_(0),
+      number_of_fallback_thumbnails_requested_(0),
+      number_of_fallback_thumbnails_used_(0) {
 }
 
 size_t NTPUserDataLogger::GetPercentError(size_t errors, size_t events) const {