chromeos/dbus: Add fake D-Bus clients for GATT client-mode.

device/bluetooth/bluetooth_chromeos_unittest.cc

Index: device/bluetooth/bluetooth_chromeos_unittest.cc
diff --git a/device/bluetooth/bluetooth_chromeos_unittest.cc b/device/bluetooth/bluetooth_chromeos_unittest.cc
index b7733dd3f701d463d0392e15787e5ded1b9d8c2f..924ea3c4078146b13ba5562266d7edad458b1de7 100644
--- a/device/bluetooth/bluetooth_chromeos_unittest.cc
+++ b/device/bluetooth/bluetooth_chromeos_unittest.cc
@@ -706,16 +706,16 @@ TEST_F(BluetoothChromeOSTest, Discovery) {
   ASSERT_EQ((size_t)1, discovery_sessions_.size());
   ASSERT_TRUE(discovery_sessions_[0]->IsActive());
 
-  // First device to appear.
+  // First two devices to appear.
   message_loop_.Run();
 
-  EXPECT_EQ(1, observer.device_added_count_);
-  EXPECT_EQ(FakeBluetoothDeviceClient::kLegacyAutopairAddress,
+  EXPECT_EQ(2, observer.device_added_count_);
+  EXPECT_EQ(FakeBluetoothDeviceClient::kLowEnergyAddress,
             observer.last_device_address_);
 
   // Next we should get another two devices...
   message_loop_.Run();
-  EXPECT_EQ(3, observer.device_added_count_);
+  EXPECT_EQ(4, observer.device_added_count_);
 
   // Okay, let's run forward until a device is actually removed...
   while (!observer.device_removed_count_)