Issue #19956: Add telemetry for tab view setting changes

This differs from `tab_view_setting` which tells us what the user's tab
setting is at startup. It does not tell us if the user explicitly
changed it instead of just using the default (which was recently
changed in #19809).

app/metrics.yaml

@@ -389,6 +389,26 @@ events:
     notification_emails:
       - android-probes@mozilla.com
     expires: "2021-12-10"
+  tab_view_changed:
+    type: event
+    description: |
+      Indicates that the user has changed their tab view
+      settings, either from the default or by personal
+      preference.
+    extra_keys:
+      type:
+        description: |
+          A string containing the name of the tab view the user tapped.
+          These items include: list or grid.
+    bugs:
+      - https://github.com/mozilla-mobile/fenix/issues/19956
+    data_reviews:
+      - https://github.com/mozilla-mobile/fenix/pull/19959#issuecomment-882539619
+    data_sensitivity:
+      - interaction
+    notification_emails:
+      - android-probes@mozilla.com
+    expires: "2022-05-10"
 
 onboarding:
   fxa_auto_signin:

app/src/main/java/org/mozilla/fenix/components/metrics/Event.kt

@@ -605,6 +605,13 @@ sealed class Event {
             get() = mapOf(Autoplay.settingChangedKeys.autoplaySetting to setting.toString().lowercase(Locale.ROOT))
     }
 
+    data class TabViewSettingChanged(val type: Type) : Event() {
+        enum class Type { LIST, GRID }
+
+        override val extras: Map<Events.tabViewChangedKeys, String>?
+            get() = mapOf(Events.tabViewChangedKeys.type to type.toString().lowercase(Locale.ROOT))
+    }
+
     sealed class Search
 
     internal open val extras: Map<*, String>?

app/src/main/java/org/mozilla/fenix/components/metrics/GleanMetricsService.kt

@@ -827,6 +827,10 @@ private val Event.wrapper: EventWrapper<*>?
         is Event.HomeScreenDisplayed -> EventWrapper<NoExtraKeys>(
             { HomeScreen.homeScreenDisplayed.record(it) }
         )
+        is Event.TabViewSettingChanged -> EventWrapper(
+            { Events.tabViewChanged.record(it) },
+            { Events.tabViewChangedKeys.valueOf(it) }
+        )
 
         is Event.BrowserToolbarHomeButtonClicked -> EventWrapper<NoExtraKeys>(
             { Events.browserToolbarHomeTapped.record(it) }

app/src/main/java/org/mozilla/fenix/settings/RadioButtonPreference.kt

@@ -32,6 +32,9 @@ open class RadioButtonPreference @JvmOverloads constructor(
     private var defaultValue: Boolean = false
     private var clickListener: (() -> Unit)? = null
 
+    val isChecked: Boolean
+        get() = radioButton?.isChecked == true
+
     init {
         layoutResource = R.layout.preference_widget_radiobutton
 

app/src/main/java/org/mozilla/fenix/settings/TabsSettingsFragment.kt

@@ -11,6 +11,8 @@ import androidx.preference.PreferenceFragmentCompat
 import org.mozilla.fenix.FeatureFlags
 import org.mozilla.fenix.R
 import org.mozilla.fenix.components.metrics.Event
+import org.mozilla.fenix.components.metrics.Event.TabViewSettingChanged
+import org.mozilla.fenix.components.metrics.Event.TabViewSettingChanged.Type
 import org.mozilla.fenix.ext.components
 import org.mozilla.fenix.ext.showToolbar
 import org.mozilla.fenix.utils.view.addToRadioGroup
@@ -66,6 +68,9 @@ class TabsSettingsFragment : PreferenceFragmentCompat() {
         requirePreference<PreferenceCategory>(R.string.pref_key_start_on_home_category).isVisible =
             FeatureFlags.showStartOnHomeSettings
 
+        listRadioButton.onClickListener(::sendTabViewTelemetry)
+        gridRadioButton.onClickListener(::sendTabViewTelemetry)
+
         setupRadioGroups()
     }
 
@@ -88,4 +93,14 @@ class TabsSettingsFragment : PreferenceFragmentCompat() {
             startOnHomeRadioNever
         )
     }
+
+    private fun sendTabViewTelemetry() {
+        val metrics = requireContext().components.analytics.metrics
+
+        if (listRadioButton.isChecked && !gridRadioButton.isChecked) {
+            metrics.track(TabViewSettingChanged(Type.LIST))
+        } else {
+            metrics.track(TabViewSettingChanged(Type.GRID))
+        }
+    }
 }