There is both ::prefs and ::metrics::prefs so be explicit

When code inside metrics say "prefs" the default assumption is
that it means "::metrics::prefs", *if* the compiler knows that
::metrics::prefs exists. This code wants to use ::prefs which
failed in jumbo build experiments where the compiler knew
that ::metrics::prefs exists.

This patch makes the namespace lookup explicit by writing
::prefs instead of just prefs.

Higher level: The coding standard discourages sub namespaces with
the same name as a top level namespace so it is possible
::metrics::prefs should change name at some time.

Bug: 746957
Change-Id: Ia68378e6a3e7937f5d1b2ebcc960b9111e426fe6
Reviewed-on: https://chromium-review.googlesource.com/890455Reviewed-by: Gayane Petrosyan <gayane@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#532934}

chrome/browser/metrics/tab_stats_data_store.cc

@@ -25,11 +25,11 @@ TabStatsDataStore::TabStatsDataStore(PrefService* pref_service)
     : pref_service_(pref_service) {
   DCHECK(pref_service != nullptr);
   tab_stats_.total_tab_count_max =
-      pref_service->GetInteger(prefs::kTabStatsTotalTabCountMax);
+      pref_service->GetInteger(::prefs::kTabStatsTotalTabCountMax);
   tab_stats_.max_tab_per_window =
-      pref_service->GetInteger(prefs::kTabStatsMaxTabsPerWindow);
+      pref_service->GetInteger(::prefs::kTabStatsMaxTabsPerWindow);
   tab_stats_.window_count_max =
-      pref_service->GetInteger(prefs::kTabStatsWindowCountMax);
+      pref_service->GetInteger(::prefs::kTabStatsWindowCountMax);
 }
 
 void TabStatsDataStore::OnWindowAdded() {
@@ -61,7 +61,7 @@ void TabStatsDataStore::UpdateMaxTabsPerWindowIfNeeded(size_t value) {
   if (value <= tab_stats_.max_tab_per_window)
     return;
   tab_stats_.max_tab_per_window = value;
-  pref_service_->SetInteger(prefs::kTabStatsMaxTabsPerWindow, value);
+  pref_service_->SetInteger(::prefs::kTabStatsMaxTabsPerWindow, value);
 }
 
 void TabStatsDataStore::ResetMaximumsToCurrentState() {
@@ -88,7 +88,7 @@ void TabStatsDataStore::UpdateTotalTabCountMaxIfNeeded() {
   if (tab_stats_.total_tab_count <= tab_stats_.total_tab_count_max)
     return;
   tab_stats_.total_tab_count_max = tab_stats_.total_tab_count;
-  pref_service_->SetInteger(prefs::kTabStatsTotalTabCountMax,
+  pref_service_->SetInteger(::prefs::kTabStatsTotalTabCountMax,
                             tab_stats_.total_tab_count_max);
 }
 
@@ -97,7 +97,7 @@ void TabStatsDataStore::UpdateWindowCountMaxIfNeeded() {
   if (tab_stats_.window_count <= tab_stats_.window_count_max)
     return;
   tab_stats_.window_count_max = tab_stats_.window_count;
-  pref_service_->SetInteger(prefs::kTabStatsWindowCountMax,
+  pref_service_->SetInteger(::prefs::kTabStatsWindowCountMax,
                             tab_stats_.window_count_max);
 }
 

chrome/browser/metrics/tab_stats_tracker.cc

@@ -58,7 +58,7 @@ TabStatsTracker::TabStatsTracker(PrefService* pref_service)
       tab_stats_data_store_(base::MakeUnique<TabStatsDataStore>(pref_service)),
       daily_event_(
           base::MakeUnique<DailyEvent>(pref_service,
-                                       prefs::kTabStatsDailySample,
+                                       ::prefs::kTabStatsDailySample,
                                        kTabStatsDailyEventHistogramName)) {
   DCHECK(pref_service != nullptr);
   // Get the list of existing windows/tabs. There shouldn't be any if this is
@@ -111,10 +111,10 @@ TabStatsTracker* TabStatsTracker::GetInstance() {
 }
 
 void TabStatsTracker::RegisterPrefs(PrefRegistrySimple* registry) {
-  registry->RegisterIntegerPref(prefs::kTabStatsTotalTabCountMax, 0);
-  registry->RegisterIntegerPref(prefs::kTabStatsMaxTabsPerWindow, 0);
-  registry->RegisterIntegerPref(prefs::kTabStatsWindowCountMax, 0);
-  DailyEvent::RegisterPref(registry, prefs::kTabStatsDailySample);
+  registry->RegisterIntegerPref(::prefs::kTabStatsTotalTabCountMax, 0);
+  registry->RegisterIntegerPref(::prefs::kTabStatsMaxTabsPerWindow, 0);
+  registry->RegisterIntegerPref(::prefs::kTabStatsWindowCountMax, 0);
+  DailyEvent::RegisterPref(registry, ::prefs::kTabStatsDailySample);
 }
 
 void TabStatsTracker::TabStatsDailyObserver::OnDailyEvent(