Kill NewTabPage.NumberOfMouseOvers.

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 "base/metrics/histogram.h"
 #include "base/strings/stringprintf.h"
@@ skipping 95 matching lines @@
 }
 
 // static
 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;
-
   // We only send statistics once per page.
   // And we don't send if there are no tiles recorded.
   if (has_emitted_ || !number_of_tiles_)
     return;
 
   // LoadTime only gets update once per page, so we don't have it on reloads.
   if (load_time_ > base::TimeDelta::FromMilliseconds(0)) {
     logLoadTimeHistogram("NewTabPage.LoadTime", load_time_);
 
     // Split between ML and MV.
@@ skipping 70 matching lines @@
       break;
     case NTP_THUMBNAIL_ERROR:
       number_of_thumbnail_errors_++;
       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:

[Marc Treib, 2016/06/24 14:48:02]

Remove the case, so it'll fall into the NOTREACHED below.

-      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();
   }
@@ skipping 62 matching lines @@
     : content::WebContentsObserver(contents),
       has_server_side_suggestions_(false),
       has_client_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),
       has_emitted_(false),
       during_startup_(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.
   if (contents) {
     ProfileSyncService* sync = ProfileSyncServiceFactory::GetForProfile(
         Profile::FromBrowserContext(contents->GetBrowserContext()));
     if (sync) {
       browser_sync::SessionsSyncManager* sessions =
           static_cast<browser_sync::SessionsSyncManager*>(
               sync->GetSessionsSyncableService());
       if (sessions) {
         sync_sessions::SyncSessionsMetrics::RecordYoungestForeignTabAgeOnNTP(
             sessions);
       }
     }
   }
 }