[Proximity Auth] Port the UnlockManager class.

components/proximity_auth/metrics.h

Index: components/proximity_auth/metrics.h
diff --git a/components/proximity_auth/metrics.h b/components/proximity_auth/metrics.h
index 5a0e20a7c3764cf59df5c7fe4202426848422647..a1ac3cd07449e8aa767b76f9d779020ee1f7cca9 100644
--- a/components/proximity_auth/metrics.h
+++ b/components/proximity_auth/metrics.h
@@ -13,6 +13,19 @@ namespace metrics {
 extern const char kUnknownDeviceModel[];
 extern const int kUnknownProximityValue;
 
+// Possible states of the remote device's security settings. This enum is used
+// to back a histogram, and hence should be treated as append-only.
+enum class RemoteSecuritySettingsState {
+  UNKNOWN,
+  SCREEN_LOCK_DISABLED_TRUST_AGENT_UNSUPPORTED,
+  SCREEN_LOCK_DISABLED_TRUST_AGENT_DISABLED,
+  SCREEN_LOCK_DISABLED_TRUST_AGENT_ENABLED,
+  SCREEN_LOCK_ENABLED_TRUST_AGENT_UNSUPPORTED,
+  SCREEN_LOCK_ENABLED_TRUST_AGENT_DISABLED,
+  SCREEN_LOCK_ENABLED_TRUST_AGENT_ENABLED,
+  COUNT
+};
+
 // Records the current |rolling_rssi| reading, upon a successful auth attempt.
 // |rolling_rssi| should be set to |kUnknownProximityValue| if no RSSI readings
 // are available.
@@ -33,6 +46,10 @@ void RecordAuthProximityTimeSinceLastZeroRssi(
 // set to |kUnknownDeviceModel| if the device model could not be read.
 void RecordAuthProximityRemoteDeviceModelHash(const std::string& device_model);
 
+// Records the screen lock and trust agent settings state of the remote device,
+// as received in a status update from the remote device.
+void RecordRemoteSecuritySettingsState(RemoteSecuritySettingsState state);
+
 }  // namespace metrics
 }  // namespace proximity_auth