Ash Tray: Add new metrics to track blocked notifiers.

BUG=1073536

Change-Id: If5988a47ff11f0bc15021c558039c3465e1a3b53
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2198602
Commit-Queue: Tim Song <tengs@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Ahmed Mehfooz <amehfooz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#769016}

ash/system/unified/quiet_mode_feature_pod_controller.cc

@@ -109,6 +109,7 @@ void QuietModeFeaturePodController::OnNotifiersUpdated(
     if (!notifier.enabled)
       ++disabled_count;
   }
+  RecordDisabledNotifierCount(disabled_count);
 
   if (disabled_count > 0) {
     button_->SetSubLabel(l10n_util::GetPluralStringFUTF16(
@@ -132,4 +133,21 @@ base::string16 QuietModeFeaturePodController::GetQuietModeStateTooltip() {
           : IDS_ASH_STATUS_TRAY_NOTIFICATIONS_DO_NOT_DISTURB_OFF_STATE);
 }
 
+void QuietModeFeaturePodController::RecordDisabledNotifierCount(
+    int disabled_count) {
+  if (!last_disabled_count_.has_value()) {
+    last_disabled_count_ = disabled_count;
+    UMA_HISTOGRAM_COUNTS_100("ChromeOS.SystemTray.BlockedNotifiersOnOpen",
+                             disabled_count);
+    return;
+  }
+
+  if (*last_disabled_count_ == disabled_count)
+    return;
+
+  last_disabled_count_ = disabled_count;
+  UMA_HISTOGRAM_COUNTS_100("ChromeOS.SystemTray.BlockedNotifiersAfterUpdate",
+                           disabled_count);
+}
+
 }  // namespace ash

ash/system/unified/quiet_mode_feature_pod_controller.h

@@ -9,6 +9,7 @@
 #include "ash/public/cpp/notifier_settings_observer.h"
 #include "ash/system/unified/feature_pod_controller_base.h"
 #include "base/macros.h"
+#include "base/optional.h"
 #include "base/strings/string16.h"
 #include "ui/message_center/message_center_observer.h"
 
@@ -44,10 +45,14 @@ class ASH_EXPORT QuietModeFeaturePodController
  private:
   base::string16 GetQuietModeStateTooltip();
 
+  void RecordDisabledNotifierCount(int disabled_count);
+
   UnifiedSystemTrayController* const tray_controller_;
 
   FeaturePodButton* button_ = nullptr;
 
+  base::Optional<int> last_disabled_count_;
+
   DISALLOW_COPY_AND_ASSIGN(QuietModeFeaturePodController);
 };
 

tools/metrics/histograms/histograms.xml

@@ -25456,6 +25456,26 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="ChromeOS.SystemTray.BlockedNotifiersAfterUpdate"
+    units="notifiers" expires_after="2021-05-10">
+  <owner>tengs@chromium.org</owner>
+  <owner>gzadina@google.com</owner>
+  <summary>
+    Tracks the number of blocked notifiers in the system tray after the user
+    blocks one or multiple notifiers. Note that this metric records the number
+    of blocked notifiers *after* the update.
+  </summary>
+</histogram>
+
+<histogram name="ChromeOS.SystemTray.BlockedNotifiersOnOpen" units="notifiers"
+    expires_after="2021-05-10">
+  <owner>tengs@chromium.org</owner>
+  <owner>gzadina@google.com</owner>
+  <summary>
+    Tracks the number of blocked notifiers in the system tray when it is opened.
+  </summary>
+</histogram>
+
 <histogram name="ChromeOS.SystemTray.FeaturePodCountOnOpen" units="count"
     expires_after="2020-10-04">
   <owner>tengs@chromium.org</owner>