[CrOS PhoneHub] Metric fixes.

* Deprecate PhoneHub.InitialConnecting as it is no longer needed, but
  was not corrected when moving metrics from ash to phonehub
* Fix PhoneHub.NotificationOptIn -> PhoneHub.NotificationOptInEvents
* Fix PhoneHub.Screen.OnSettingsButtonClicked ->
  honeHub.Screen.ScreenOnSettingsButtonClicked

Note that following metrics currently emit properly on ToT
(manually visible from chrome://histograms):

PhoneHub.InterstitialScreenEvent.BluetoothOrWifiDisabled
PhoneHub.InterstitialScreenEvent.Onboarding.ExistingMultideviceUser
PhoneHub.InterstitialScreenEvent.OnboardingDismissPrompt

Fixed: 1164584
Bug: 1106937
Change-Id: I977a3e454c9ed0add6e0efc669a45dc6349c5110
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2625277
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843329}

ash/system/phonehub/phone_hub_metrics.cc

@@ -52,12 +52,12 @@ void LogScreenOnBubbleClose(Screen screen) {
 }
 
 void LogScreenOnSettingsButtonClicked(Screen screen) {
-  base::UmaHistogramEnumeration("PhoneHub.Screen.OnSettingsButtonClicked",
+  base::UmaHistogramEnumeration("PhoneHub.ScreenOnSettingsButtonClicked",
                                 screen);
 }
 
 void LogNotificationOptInEvent(InterstitialScreenEvent event) {
-  base::UmaHistogramEnumeration("PhoneHub.NotificationOptIn", event);
+  base::UmaHistogramEnumeration("PhoneHub.NotificationOptInEvents", event);
 }
 
 void LogTabContinuationChipClicked(int tab_index) {

tools/metrics/histograms/histograms_xml/phonehub/histograms.xml

@@ -110,7 +110,11 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
   <token key="Screen">
     <variant name="BluetoothOrWifiDisabled"/>
-    <variant name="InitialConnecting"/>
+    <variant name="InitialConnecting">
+      <obsolete>
+        Combined into PhoneConnecting on Nov 2020.
+      </obsolete>
+    </variant>
     <variant name="Onboarding.ExistingMultideviceUser"/>
     <variant name="Onboarding.NewMultideviceUser"/>
     <variant name="OnboardingDismissPrompt"/>
@@ -139,6 +143,16 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="PhoneHub.NotificationOptIn"
+    enum="PhoneHubInterstitialScreenEvent" expires_after="2021-10-31">
+  <obsolete>
+    Renamed to PhoneHub.NotificationOptInEvents on 1/2021 in M89.
+  </obsolete>
+  <owner>tengs@chromium.org</owner>
+  <owner>khorimoto@chromium.org</owner>
+  <summary>Events for the given notification opt-in prompt.</summary>
+</histogram>
+
 <histogram name="PhoneHub.NotificationOptInEvents"
     enum="PhoneHubInterstitialScreenEvent" expires_after="2021-10-31">
   <owner>tengs@chromium.org</owner>
@@ -160,6 +174,19 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   <summary>Event logged after the user clicks on a quick action.</summary>
 </histogram>
 
+<histogram name="PhoneHub.Screen.OnSettingsButtonClicked" enum="PhoneHubScreen"
+    expires_after="2021-10-31">
+  <obsolete>
+    Renamed to PhoneHub.ScreenOnSettingsButtonClicked on 1/2021 in M89.
+  </obsolete>
+  <owner>tengs@chromium.org</owner>
+  <owner>khorimoto@chromium.org</owner>
+  <summary>
+    Logs the current screen when the settings button is clicked in the tray
+    bubble.
+  </summary>
+</histogram>
+
 <histogram name="PhoneHub.ScreenOnSettingsButtonClicked" enum="PhoneHubScreen"
     expires_after="2021-10-31">
   <owner>tengs@chromium.org</owner>