BluetoothAdapterMac::LowEnergyDeviceUpdated() Implemented

device/bluetooth/bluetooth_adapter_mac.mm

Index: device/bluetooth/bluetooth_adapter_mac.mm
diff --git a/device/bluetooth/bluetooth_adapter_mac.mm b/device/bluetooth/bluetooth_adapter_mac.mm
index 0dfb7991ca4587d78faca8c4378900d86dbc08a7..3c60c6b8c868d1fd898c65dbee749cb37817fded 100644
--- a/device/bluetooth/bluetooth_adapter_mac.mm
+++ b/device/bluetooth/bluetooth_adapter_mac.mm
@@ -388,11 +388,35 @@ void BluetoothAdapterMac::ClassicDeviceAdded(IOBluetoothDevice* device) {
                     DeviceAdded(this, devices_[device_address]));
 }
 
-// TODO(krstnmnlsn): Implement method. http://crbug.com/496987.
 void BluetoothAdapterMac::LowEnergyDeviceUpdated(
     CBPeripheral* peripheral,
     NSDictionary* advertisementData,
     int rssi) {
+  std::string device_address =
+      BluetoothLowEnergyDeviceMac::GetPeripheralHashAddress(peripheral);
+
+  if (devices_.count(device_address)) {

[scheib, 2015/07/08 05:20:36]

Push back if you like, but here's my take on testing for the device existence
and then inserting or updating it without searching through the map again.
https://codereview.chromium.org/1215303006/diff/60001/device/bluetooth/blueto...

 BluetoothDevice*& device = devices_[address];
 if (!device) {
   device = // new BluetoothDevice...
 } else {
   // use device->member

Your current code does a search for the address 3 times for an update, or 2
times for a new device.

[krstnmnlsn, 2015/07/13 17:26:23]

Done.

+    if (devices_[device_address]->GetIdentifier() !=
+        BluetoothLowEnergyDeviceMac::GetPeripheralIdentifier(peripheral)) {
+      // Collision, two identifiers map to the same hash address.  With a 48 bit
+      // hash the probability of this occuring with 10,000 devices
+      // simultaneously present is 1e-6, so we simply return.

[scheib, 2015/07/08 05:20:36]

Cite the source for those numbers. Also explain handling it a bit more. ", so we
ignore the device found later by returning."

[krstnmnlsn, 2015/07/13 17:26:23]

Done.

+      return;
+    }
+    // A device has an update.
+    BluetoothLowEnergyDeviceMac* old_device =
+        static_cast<BluetoothLowEnergyDeviceMac*>(devices_[device_address]);
+    old_device->Update(peripheral, advertisementData, rssi);
+    FOR_EACH_OBSERVER(BluetoothAdapter::Observer, observers_,

[scheib, 2015/07/08 05:20:36]

I think only call DeviceChanged if data about the device did change.
(old_device->Update could return a bool to let us know).

[krstnmnlsn, 2015/07/13 17:26:23]

(after offline discussion) leaving this for now, at least until it becomes clear
which changes to the peripheral we do and do not care about.

[scheib, 2015/07/13 18:24:39]

Acknowledged.

+                      DeviceChanged(this, old_device));
+    return;
+  }
+
+  // A new device has been found.
+  devices_[device_address] =
+      new BluetoothLowEnergyDeviceMac(peripheral, advertisementData, rssi);
+  FOR_EACH_OBSERVER(BluetoothAdapter::Observer, observers_,
+                    DeviceAdded(this, devices_[device_address]));
 }
 
 void BluetoothAdapterMac::RemoveTimedOutDevices() {