For #17869 - Start the Android Keystore experiment

Only on API 23+ (minimum Android version needed for SecureAbove22Preferences)
and only if enabled by a Nimbus experiment.

The Nimbus experiment will have the key `fenix-android-keystore` and use the
default branches - "control" and "treatment".

app/src/main/java/org/mozilla/fenix/FenixApplication.kt

@@ -48,6 +48,7 @@ import org.mozilla.fenix.GleanMetrics.Metrics
 import org.mozilla.fenix.GleanMetrics.PerfStartup
 import org.mozilla.fenix.components.Components
 import org.mozilla.fenix.components.metrics.MetricServiceType
+import org.mozilla.fenix.components.metrics.SecurePrefsTelemetry
 import org.mozilla.fenix.ext.settings
 import org.mozilla.fenix.perf.ProfilerMarkerFactProcessor
 import org.mozilla.fenix.perf.StartupTimeline
@@ -218,6 +219,8 @@ open class FenixApplication : LocaleAwareApplication(), Provider {
                         components.core.bookmarksStorage.warmUp()
                         components.core.passwordsStorage.warmUp()
                     }
+
+                    SecurePrefsTelemetry(this@FenixApplication, components.analytics.experiments).startTests()
                 }
                 // Account manager initialization needs to happen on the main thread.
                 GlobalScope.launch(Dispatchers.Main) {

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

@@ -0,0 +1,35 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.components.metrics
+
+import android.content.Context
+import android.os.Build
+import mozilla.components.lib.dataprotect.SecurePrefsReliabilityExperiment
+import mozilla.components.service.nimbus.NimbusApi
+import org.mozilla.fenix.experiments.ExperimentBranch
+import org.mozilla.fenix.experiments.Experiments
+import org.mozilla.fenix.ext.withExperiment
+
+/**
+ * Allows starting a quick test of ACs SecureAbove22Preferences that will emit Facts
+ * for the basic operations and allow us to log them for later evaluation of APIs stability.
+ */
+class SecurePrefsTelemetry(
+    private val appContext: Context,
+    private val experiments: NimbusApi
+) {
+    suspend fun startTests() {
+        // The Android Keystore is used to secure the shared prefs only on API 23+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            // These tests should run only if the experiment is live
+            experiments.withExperiment(Experiments.ANDROID_KEYSTORE) { experimentBranch ->
+                // .. and this device is not in the control group.
+                if (experimentBranch == ExperimentBranch.TREATMENT) {
+                        SecurePrefsReliabilityExperiment(appContext)()
+                }
+            }
+        }
+    }
+}

app/src/main/java/org/mozilla/fenix/experiments/Experiments.kt

@@ -8,6 +8,7 @@ class Experiments {
     companion object {
         const val A_A_NIMBUS_VALIDATION = "fenix-nimbus-validation-v3"
         const val BOOKMARK_ICON = "fenix-bookmark-list-icon"
+        const val ANDROID_KEYSTORE = "fenix-android-keystore"
     }
 }