[EasyUnlock] Update ProximityMonitor to only check for RSSI proximity.

components/proximity_auth/proximity_monitor_impl.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/proximity_auth/proximity_monitor_impl.h"
 
 #include <math.h>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/tick_clock.h"
 #include "base/time/time.h"
 #include "components/proximity_auth/logging/logging.h"
 #include "components/proximity_auth/metrics.h"
 #include "components/proximity_auth/proximity_monitor_observer.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 #include "device/bluetooth/bluetooth_adapter_factory.h"
 
 using device::BluetoothDevice;
 
 namespace proximity_auth {
 
 // The time to wait, in milliseconds, between proximity polling iterations.
 const int kPollingTimeoutMs = 250;
 
 // The RSSI threshold below which we consider the remote device to not be in
 // proximity.
-const int kRssiThreshold = -5;
+const int kRssiThreshold = -45;
 
 // The weight of the most recent RSSI sample.
 const double kRssiSampleWeight = 0.3;
 
 ProximityMonitorImpl::ProximityMonitorImpl(
-    const cryptauth::RemoteDevice& remote_device,
+    cryptauth::Connection* connection,
     std::unique_ptr<base::TickClock> clock)
-    : remote_device_(remote_device),
-      strategy_(Strategy::NONE),
+    : connection_(connection),
       remote_device_is_in_proximity_(false),
       is_active_(false),
       clock_(std::move(clock)),
       polling_weak_ptr_factory_(this),
       weak_ptr_factory_(this) {
   if (device::BluetoothAdapterFactory::IsBluetoothSupported()) {
     device::BluetoothAdapterFactory::GetAdapter(
         base::Bind(&ProximityMonitorImpl::OnAdapterInitialized,
                    weak_ptr_factory_.GetWeakPtr()));
   } else {
     PA_LOG(ERROR) << "[Proximity] Proximity monitoring unavailable: "
                   << "Bluetooth is unsupported on this platform.";
   }
-
-  // TODO(isherman): Test prefs to set the strategy. Need to read from "Local
-  // State" prefs on the sign-in screen, and per-user prefs on the lock screen.
-  // TODO(isherman): Unlike in the JS app, destroy and recreate the proximity
-  // monitor when the connection state changes.
 }
 
 ProximityMonitorImpl::~ProximityMonitorImpl() {
 }
 
 void ProximityMonitorImpl::Start() {
   is_active_ = true;
   UpdatePollingState();
 }
 
 void ProximityMonitorImpl::Stop() {
   is_active_ = false;
   ClearProximityState();
   UpdatePollingState();
 }
 
-ProximityMonitor::Strategy ProximityMonitorImpl::GetStrategy() const {
-  return strategy_;
-}
-
 bool ProximityMonitorImpl::IsUnlockAllowed() const {
-  return strategy_ == Strategy::NONE || remote_device_is_in_proximity_;
-}
-
-bool ProximityMonitorImpl::IsInRssiRange() const {
-  return (strategy_ != Strategy::NONE && rssi_rolling_average_ &&
-          *rssi_rolling_average_ > kRssiThreshold);
+  return remote_device_is_in_proximity_;
 }
 
 void ProximityMonitorImpl::RecordProximityMetricsOnAuthSuccess() {
   double rssi_rolling_average = rssi_rolling_average_
                                     ? *rssi_rolling_average_
                                     : metrics::kUnknownProximityValue;
 
-  int last_transmit_power_delta =
-      last_transmit_power_reading_
-          ? (last_transmit_power_reading_->transmit_power -
-             last_transmit_power_reading_->max_transmit_power)
-          : metrics::kUnknownProximityValue;
-
-  // If no zero RSSI value has been read, then record an overflow.
-  base::TimeDelta time_since_last_zero_rssi;
-  if (last_zero_rssi_timestamp_)
-    time_since_last_zero_rssi = clock_->NowTicks() - *last_zero_rssi_timestamp_;
-  else
-    time_since_last_zero_rssi = base::TimeDelta::FromDays(100);
-
   std::string remote_device_model = metrics::kUnknownDeviceModel;
-  if (remote_device_.name != remote_device_.bluetooth_address)
-    remote_device_model = remote_device_.name;
+  cryptauth::RemoteDevice remote_device = connection_->remote_device();
+  if (!remote_device.name.empty())
+    remote_device_model = remote_device.name;
 
   metrics::RecordAuthProximityRollingRssi(round(rssi_rolling_average));
-  metrics::RecordAuthProximityTransmitPowerDelta(last_transmit_power_delta);
-  metrics::RecordAuthProximityTimeSinceLastZeroRssi(time_since_last_zero_rssi);
   metrics::RecordAuthProximityRemoteDeviceModelHash(remote_device_model);
 }
 
 void ProximityMonitorImpl::AddObserver(ProximityMonitorObserver* observer) {
   observers_.AddObserver(observer);
 }
 
 void ProximityMonitorImpl::RemoveObserver(ProximityMonitorObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
-void ProximityMonitorImpl::SetStrategy(Strategy strategy) {
-  if (strategy_ == strategy)
-    return;
-  strategy_ = strategy;
-  CheckForProximityStateChange();
-  UpdatePollingState();
-}
-
-ProximityMonitorImpl::TransmitPowerReading::TransmitPowerReading(
-    int transmit_power,
-    int max_transmit_power)
-    : transmit_power(transmit_power), max_transmit_power(max_transmit_power) {
-}
-
-bool ProximityMonitorImpl::TransmitPowerReading::IsInProximity() const {
-  return transmit_power < max_transmit_power;
-}
-
 void ProximityMonitorImpl::OnAdapterInitialized(
     scoped_refptr<device::BluetoothAdapter> adapter) {
   bluetooth_adapter_ = adapter;
   UpdatePollingState();
 }
 
 void ProximityMonitorImpl::UpdatePollingState() {
   if (ShouldPoll()) {
     // If there is a polling iteration already scheduled, wait for it.
     if (polling_weak_ptr_factory_.HasWeakPtrs())
@@ skipping 12 matching lines @@
     remote_device_is_in_proximity_ = false;
   }
 }
 
 void ProximityMonitorImpl::PerformScheduledUpdatePollingState() {
   polling_weak_ptr_factory_.InvalidateWeakPtrs();
   UpdatePollingState();
 }
 
 bool ProximityMonitorImpl::ShouldPoll() const {
-  // Note: We poll even if the strategy is NONE so we can record measurements.
   return is_active_ && bluetooth_adapter_;
 }
 
 void ProximityMonitorImpl::Poll() {
   DCHECK(ShouldPoll());
 
-  BluetoothDevice* device =
-      bluetooth_adapter_->GetDevice(remote_device_.bluetooth_address);
+  std::string address = connection_->GetDeviceAddress();
+  BluetoothDevice* device = bluetooth_adapter_->GetDevice(address);
 
   if (!device) {
-    PA_LOG(ERROR) << "Unknown Bluetooth device with address "
-                  << remote_device_.bluetooth_address;
+    PA_LOG(ERROR) << "Unknown Bluetooth device with address " << address;
     ClearProximityState();
     return;
   }
   if (!device->IsConnected()) {
-    PA_LOG(ERROR) << "Bluetooth device with address "
-                  << remote_device_.bluetooth_address << " is not connected.";
+    PA_LOG(ERROR) << "Bluetooth device with address " << address
+                  << " is not connected.";
     ClearProximityState();
     return;
   }
 
   device->GetConnectionInfo(base::Bind(&ProximityMonitorImpl::OnConnectionInfo,
                                        weak_ptr_factory_.GetWeakPtr()));
 }
 
 void ProximityMonitorImpl::OnConnectionInfo(
     const BluetoothDevice::ConnectionInfo& connection_info) {
   if (!is_active_) {
     PA_LOG(INFO) << "[Proximity] Got connection info after stopping";
     return;
   }
 
-  if (connection_info.rssi != BluetoothDevice::kUnknownPower &&
-      connection_info.transmit_power != BluetoothDevice::kUnknownPower &&
-      connection_info.max_transmit_power != BluetoothDevice::kUnknownPower) {
+  if (connection_info.rssi != BluetoothDevice::kUnknownPower) {
     AddSample(connection_info);
   } else {
     PA_LOG(WARNING) << "[Proximity] Unkown values received from API: "
-                    << connection_info.rssi << " "
-                    << connection_info.transmit_power << " "
-                    << connection_info.max_transmit_power;
+                    << connection_info.rssi;
     rssi_rolling_average_.reset();
-    last_transmit_power_reading_.reset();
     CheckForProximityStateChange();
   }
 }
 
 void ProximityMonitorImpl::ClearProximityState() {
   if (is_active_ && remote_device_is_in_proximity_) {
     for (auto& observer : observers_)
       observer.OnProximityStateChanged();
   }
 
   remote_device_is_in_proximity_ = false;
   rssi_rolling_average_.reset();
-  last_transmit_power_reading_.reset();
-  last_zero_rssi_timestamp_.reset();
 }
 
 void ProximityMonitorImpl::AddSample(
     const BluetoothDevice::ConnectionInfo& connection_info) {
   double weight = kRssiSampleWeight;
   if (!rssi_rolling_average_) {
     rssi_rolling_average_.reset(new double(connection_info.rssi));
   } else {
     *rssi_rolling_average_ =
         weight * connection_info.rssi + (1 - weight) * (*rssi_rolling_average_);
   }
-  last_transmit_power_reading_.reset(new TransmitPowerReading(
-      connection_info.transmit_power, connection_info.max_transmit_power));
-
-  // It's rare but possible for the RSSI to be positive briefly.
-  if (connection_info.rssi >= 0)
-    last_zero_rssi_timestamp_.reset(new base::TimeTicks(clock_->NowTicks()));
 
   CheckForProximityStateChange();
 }
 
 void ProximityMonitorImpl::CheckForProximityStateChange() {
-  if (strategy_ == Strategy::NONE)
-    return;
+  bool is_now_in_proximity =
+      rssi_rolling_average_ && *rssi_rolling_average_ > kRssiThreshold;
 
-  bool is_now_in_proximity = false;
-  switch (strategy_) {
-    case Strategy::NONE:
-      return;
-
-    case Strategy::CHECK_RSSI:
-      is_now_in_proximity = IsInRssiRange();
-      break;
-
-    case Strategy::CHECK_TRANSMIT_POWER:
-      is_now_in_proximity = (last_transmit_power_reading_ &&
-                             last_transmit_power_reading_->IsInProximity());
-      break;
+  if (rssi_rolling_average_) {
+    LOG(WARNING) << "RSSI: " << *rssi_rolling_average_;
   }
 
   if (remote_device_is_in_proximity_ != is_now_in_proximity) {
     PA_LOG(INFO) << "[Proximity] Updated proximity state: "
                  << (is_now_in_proximity ? "proximate" : "distant");
     remote_device_is_in_proximity_ = is_now_in_proximity;
     for (auto& observer : observers_)
       observer.OnProximityStateChanged();
   }
 }
 
 }  // namespace proximity_auth