Adds a new UMA histogram to measure the NTP load time since navigation

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 "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/search/most_visited_iframe_source.h"
@@ skipping 75 matching lines @@
 std::string NTPUserDataLogger::GetMostVisitedNavigationHistogramNameForProvider(
     const std::string& provider) {
   return base::StringPrintf(kMostVisitedNavigationHistogramWithProvider,
                             provider.c_str());
 }
 
 void NTPUserDataLogger::EmitNtpStatistics() {
   UMA_HISTOGRAM_COUNTS("NewTabPage.NumberOfMouseOvers", number_of_mouseovers_);
   number_of_mouseovers_ = 0;
 
-  // Only log the following statistics if at least one tile is recorded. This
-  // check is required because the statistics are emitted whenever the user
-  // changes tab away from the NTP. However, if the user comes back to that NTP
-  // later the statistics are not regenerated (i.e. they are all 0). If we log
-  // them again we get a strong bias.
-  if (number_of_tiles_ > 0) {
-    UMA_HISTOGRAM_ENUMERATION(
-        "NewTabPage.SuggestionsType",
-        has_server_side_suggestions_ ? SERVER_SIDE : CLIENT_SIDE,
-        SUGGESTIONS_TYPE_COUNT);
-    has_server_side_suggestions_ = false;
-    UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfTiles", number_of_tiles_);
-    number_of_tiles_ = 0;
-    UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfThumbnailTiles",
-                            number_of_thumbnail_tiles_);
-    number_of_thumbnail_tiles_ = 0;
-    UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfGrayTiles",
-                            number_of_gray_tiles_);
-    number_of_gray_tiles_ = 0;
-    UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfExternalTiles",
-                            number_of_external_tiles_);
-    number_of_external_tiles_ = 0;
-    UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfThumbnailErrors",
-                            number_of_thumbnail_errors_);
-    number_of_thumbnail_errors_ = 0;
-    UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfGrayTileFallbacks",
-                            number_of_gray_tile_fallbacks_);
-    number_of_gray_tile_fallbacks_ = 0;
-    UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfExternalTileFallbacks",
-                            number_of_external_tile_fallbacks_);
-    number_of_external_tile_fallbacks_ = 0;
+  // We already sent statistics for this page once.
+  if (has_emitted_) {

[Dan Beam, 2015/03/17 01:18:46]

no curlies

[fserb, 2015/03/17 16:02:17]

Done.

+    return;
   }
+
+  // Only log the following statistics if at least one tile is recorded.
+  if (!number_of_tiles_) {

[Dan Beam, 2015/03/17 01:18:46]

nit: can you combine with if above?

[fserb, 2015/03/17 16:02:17]

Done.

+    return;
+  }
+
+  UMA_HISTOGRAM_ENUMERATION(
+      "NewTabPage.SuggestionsType",
+      has_server_side_suggestions_ ? SERVER_SIDE : CLIENT_SIDE,
+      SUGGESTIONS_TYPE_COUNT);
+  has_server_side_suggestions_ = false;
+  UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfTiles", number_of_tiles_);
+  number_of_tiles_ = 0;
+  UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfThumbnailTiles",
+                          number_of_thumbnail_tiles_);
+  number_of_thumbnail_tiles_ = 0;
+  UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfGrayTiles",
+                          number_of_gray_tiles_);
+  number_of_gray_tiles_ = 0;
+  UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfExternalTiles",
+                          number_of_external_tiles_);
+  number_of_external_tiles_ = 0;
+  UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfThumbnailErrors",
+                          number_of_thumbnail_errors_);
+  number_of_thumbnail_errors_ = 0;
+  UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfGrayTileFallbacks",
+                          number_of_gray_tile_fallbacks_);
+  number_of_gray_tile_fallbacks_ = 0;
+  UMA_HISTOGRAM_NTP_TILES("NewTabPage.NumberOfExternalTileFallbacks",
+                          number_of_external_tile_fallbacks_);
+  number_of_external_tile_fallbacks_ = 0;
+  UMA_HISTOGRAM_CUSTOM_TIMES("NewTabPage.LoadTime",
+                             base::TimeDelta::FromMilliseconds(load_time_),
+                             base::TimeDelta::FromMilliseconds(1),
+                             base::TimeDelta::FromSeconds(60), 100);
+  load_time_ = 0;
+  has_emitted_ = true;
 }
 
 void NTPUserDataLogger::LogEvent(NTPLoggingEventType event, uint64 time) {
   switch (event) {
     case NTP_SERVER_SIDE_SUGGESTION:
       has_server_side_suggestions_ = true;
       break;
     case NTP_CLIENT_SIDE_SUGGESTION:
       // We should never get a mix of server and client side suggestions,
       // otherwise there could be a race condition depending on the order in
@@ skipping 17 matching lines @@
       break;
     case NTP_GRAY_TILE_FALLBACK:
       number_of_gray_tile_fallbacks_++;
       break;
     case NTP_EXTERNAL_TILE_FALLBACK:
       number_of_external_tile_fallbacks_++;
       break;
     case NTP_MOUSEOVER:
       number_of_mouseovers_++;
       break;
+    case NTP_TILE_LOADED:
+      // The time at which the last tile has loaded (title, thumbnail or single)
+      // is a good proxy for the total load time of the NTP, therefore we keep
+      // the max as the load time.
+      load_time_ = std::max(load_time_, time);
+      break;
     default:
       NOTREACHED();
   }
 }
 
 void NTPUserDataLogger::LogMostVisitedImpression(
     int position, const base::string16& provider) {
   // Log the Most Visited navigation for navigations that have providers and
   // those that dont.
   UMA_HISTOGRAM_ENUMERATION(kMostVisitedImpressionHistogramName, position,
@@ skipping 54 matching lines @@
 NTPUserDataLogger::NTPUserDataLogger(content::WebContents* contents)
     : content::WebContentsObserver(contents),
       has_server_side_suggestions_(false),
       number_of_tiles_(0),
       number_of_thumbnail_tiles_(0),
       number_of_gray_tiles_(0),
       number_of_external_tiles_(0),
       number_of_thumbnail_errors_(0),
       number_of_gray_tile_fallbacks_(0),
       number_of_external_tile_fallbacks_(0),
-      number_of_mouseovers_(0) {
+      number_of_mouseovers_(0),
+      load_time_(0),
+      has_emitted_(false) {
 }