Cleanup desktop NTP metrics recording, part 2

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 <algorithm>
 #include <string>
 
 #include "base/metrics/histogram_macros.h"
@@ skipping 104 matching lines @@
     DVLOG(1) << "NTP URL changed from \"" << logger->ntp_url_ << "\" to \""
              << entry->GetURL() << "\"";
     logger->ntp_url_ = entry->GetURL();
   }
 
   return logger;
 }
 
 void NTPUserDataLogger::LogEvent(NTPLoggingEventType event,
                                  base::TimeDelta time) {
-  switch (event) {
-    case NTP_SERVER_SIDE_SUGGESTION:
-      has_server_side_suggestions_ = true;
-      number_of_tiles_++;
-      return;
-    case NTP_CLIENT_SIDE_SUGGESTION:
-      has_client_side_suggestions_ = true;
-      number_of_tiles_++;
-      return;
-    case NTP_ALL_TILES_LOADED:
-      EmitNtpStatistics(time);
-      return;
-  }
-  NOTREACHED();
+  DCHECK_EQ(NTP_ALL_TILES_LOADED, event);
+  EmitNtpStatistics(time);
 }
 
 void NTPUserDataLogger::LogMostVisitedImpression(
     int position, NTPLoggingTileSource tile_source) {
   if ((position >= kNumMostVisited) || impression_was_logged_[position]) {
     return;
   }
   impression_was_logged_[position] = true;
 
+  switch (tile_source) {
+    case NTPLoggingTileSource::CLIENT:
+      has_client_side_suggestions_ = true;
+      break;
+    case NTPLoggingTileSource::SERVER:
+      has_server_side_suggestions_ = true;
+      break;
+  }
+
   UMA_HISTOGRAM_ENUMERATION(kMostVisitedImpressionHistogramName, position,
                             kNumMostVisited);
 
   // Cannot rely on UMA histograms macro because the name of the histogram is
   // generated dynamically.
   base::HistogramBase* counter = base::LinearHistogram::FactoryGet(
       base::StringPrintf(kMostVisitedImpressionHistogramWithProvider,
                          GetSourceName(tile_source).c_str()),
       1,
       kNumMostVisited,
@@ skipping 20 matching lines @@
 
   // Records the action. This will be available as a time-stamped stream
   // server-side and can be used to compute time-to-long-dwell.
   content::RecordAction(base::UserMetricsAction("MostVisited_Clicked"));
 }
 
 NTPUserDataLogger::NTPUserDataLogger(content::WebContents* contents)
     : content::WebContentsObserver(contents),
       has_server_side_suggestions_(false),
       has_client_side_suggestions_(false),
-      number_of_tiles_(0),
       has_emitted_(false),
       during_startup_(!AfterStartupTaskUtils::IsBrowserStartupComplete()) {
   // We record metrics about session data here because when this class typically
   // emits metrics it is too late. This session data would theoretically have
   // been used to populate the page, and we want to learn about its state when
   // the NTP is being generated.
   RecordSyncSessionMetrics(contents);
 }
 
 // content::WebContentsObserver override
 void NTPUserDataLogger::NavigationEntryCommitted(
     const content::LoadCommittedDetails& load_details) {
   NavigatedFromURLToURL(load_details.previous_url,
                         load_details.entry->GetURL());
 }
 
 void NTPUserDataLogger::NavigatedFromURLToURL(const GURL& from,
                                               const GURL& to) {
   // User is returning to NTP, probably via the back button; reset stats.
   if (from.is_valid() && to.is_valid() && (to == ntp_url_)) {
     DVLOG(1) << "Returning to New Tab Page";
     impression_was_logged_.reset();
     has_emitted_ = false;
-    number_of_tiles_ = 0;
     has_server_side_suggestions_ = false;
     has_client_side_suggestions_ = false;
   }
 }
 
 void NTPUserDataLogger::EmitNtpStatistics(base::TimeDelta load_time) {
   // We only send statistics once per page.
   if (has_emitted_)
     return;
+
+  size_t number_of_tiles = impression_was_logged_.count();
   DVLOG(1) << "Emitting NTP load time: " << load_time << ", "
-           << "number of tiles: " << number_of_tiles_;
+           << "number of tiles: " << number_of_tiles;
 
   LogLoadTimeHistogram("NewTabPage.LoadTime", load_time);
 
   // Split between ML and MV.
   std::string type = has_server_side_suggestions_ ?
       "MostLikely" : "MostVisited";
   LogLoadTimeHistogram("NewTabPage.LoadTime." + type, load_time);
   // Split between Web and Local.
   std::string source = ntp_url_.SchemeIsHTTPOrHTTPS() ? "Web" : "LocalNTP";
   LogLoadTimeHistogram("NewTabPage.LoadTime." + source, load_time);
 
   // Split between Startup and non-startup.
   std::string status = during_startup_ ? "Startup" : "NewTab";
   LogLoadTimeHistogram("NewTabPage.LoadTime." + status, load_time);
 
-  has_server_side_suggestions_ = false;
-  has_client_side_suggestions_ = false;
   UMA_HISTOGRAM_CUSTOM_COUNTS(
-      "NewTabPage.NumberOfTiles", number_of_tiles_, 1, kNumMostVisited,
+      "NewTabPage.NumberOfTiles", number_of_tiles, 1, kNumMostVisited,
       kNumMostVisited + 1);
-  number_of_tiles_ = 0;
   has_emitted_ = true;
   during_startup_ = false;
 }