Notify the BluetoothAdapter::Observer when a bluetooth peripheral disconnects on Android and Mac.

device/bluetooth/bluetooth_device_unittest.cc

Index: device/bluetooth/bluetooth_device_unittest.cc
diff --git a/device/bluetooth/bluetooth_device_unittest.cc b/device/bluetooth/bluetooth_device_unittest.cc
index 0b075e250d02187bba5c4bd989889af0079a1a9c..6ac2f63c374bf7c53a2d67bc8d1cc31b4790d750 100644
--- a/device/bluetooth/bluetooth_device_unittest.cc
+++ b/device/bluetooth/bluetooth_device_unittest.cc
@@ -158,6 +158,30 @@ TEST_F(BluetoothTest, CreateGattConnection) {
 #endif  // defined(OS_ANDROID) || defined(OS_MACOSX)
 
 #if defined(OS_ANDROID) || defined(OS_MACOSX)
+TEST_F(BluetoothTest, DisconnectionNotifiesDeviceChanged) {
+  if (!PlatformSupportsLowEnergy()) {
+    LOG(WARNING) << "Low Energy Bluetooth unavailable, skipping unit test.";
+    return;
+  }
+  InitWithFakeAdapter();
+  TestBluetoothAdapterObserver observer(adapter_);
+  StartLowEnergyDiscoverySession();
+  BluetoothDevice* device = SimulateLowEnergyDevice(3);
+  device->CreateGattConnection(GetGattConnectionCallback(Call::EXPECTED),
+                               GetConnectErrorCallback(Call::NOT_EXPECTED));
+  SimulateGattConnection(device);
+  EXPECT_EQ(1, observer.device_changed_count());
+  EXPECT_TRUE(device->IsConnected());
+  EXPECT_TRUE(device->IsGattConnected());
+
+  SimulateGattDisconnection(device);
+  EXPECT_EQ(2, observer.device_changed_count());
+  EXPECT_FALSE(device->IsConnected());
+  EXPECT_FALSE(device->IsGattConnected());
+}
+#endif  // defined(OS_ANDROID) || defined(OS_MACOSX)
+
+#if defined(OS_ANDROID) || defined(OS_MACOSX)
 // Creates BluetoothGattConnection instances and tests that the interface
 // functions even when some Disconnect and the BluetoothDevice is destroyed.
 TEST_F(BluetoothTest, BluetoothGattConnection) {