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

 // Copyright 2013 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.
 
 #include "chrome/browser/ui/webui/ntp/ntp_user_data_logger.h"
 
 #include "base/metrics/histogram.h"
 #include "chrome/browser/search/search.h"
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/navigation_details.h"
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(NTPUserDataLogger);
 
 NTPUserDataLogger::~NTPUserDataLogger() {}
 
 void NTPUserDataLogger::EmitThumbnailErrorRate() {
   DCHECK_LE(number_of_thumbnail_errors_, number_of_thumbnail_attempts_);
+  DCHECK_LE(number_of_fallback_thumbnails_used_,
+            number_of_fallback_thumbnails_requested_);

[Alexei Svitkine (slow), 2013/09/05 14:59:25]

Nit: Move this above the if block that logs it.

[beaudoin, 2013/09/05 15:02:55]

Done.

   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_));
+  }
+  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() {
   UMA_HISTOGRAM_COUNTS("NewTabPage.NumberOfMouseOvers", number_of_mouseovers_);
   number_of_mouseovers_ = 0;
 }
 
 void NTPUserDataLogger::LogEvent(NTPLoggingEventType event) {
   switch (event) {
     case NTP_MOUSEOVER:
       number_of_mouseovers_++;
       break;
     case NTP_THUMBNAIL_ATTEMPT:
       number_of_thumbnail_attempts_++;
       break;
     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();
   }
 }
 
 // content::WebContentsObserver override
 void NTPUserDataLogger::NavigationEntryCommitted(
     const content::LoadCommittedDetails& load_details) {
   if (!load_details.previous_url.is_valid())
     return;
 
   if (chrome::MatchesOriginAndPath(ntp_url_, load_details.previous_url)) {
     EmitMouseoverCount();
     // Only log thumbnail error rates for Instant NTP pages, as we do not have
     // this data for non-Instant NTPs.
     if (ntp_url_ != GURL(chrome::kChromeUINewTabURL))
       EmitThumbnailErrorRate();
   }
 }
 
 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 {
   return (100 * errors) / events;
 }