Implement the gattserverdisconnected event.

content/shell/browser/layout_test/layout_test_bluetooth_adapter_provider.h

Index: content/shell/browser/layout_test/layout_test_bluetooth_adapter_provider.h
diff --git a/content/shell/browser/layout_test/layout_test_bluetooth_adapter_provider.h b/content/shell/browser/layout_test/layout_test_bluetooth_adapter_provider.h
index 9e56fa3c8cbbb7eeb187c342a12dbc3998a93895..fecafb9f1f6f80bb6e0ce5f935c5db334c590a46 100644
--- a/content/shell/browser/layout_test/layout_test_bluetooth_adapter_provider.h
+++ b/content/shell/browser/layout_test/layout_test_bluetooth_adapter_provider.h
@@ -182,6 +182,23 @@ class LayoutTestBluetoothAdapterProvider {
   static scoped_refptr<testing::NiceMock<device::MockBluetoothAdapter>>
   GetHeartRateAdapter();
 
+  // |DisconnectingHeartRateAdapter|
+  // Inherits from |HeartRateAdapter|
+  // Internal Structure:
+  //   - Heart Rate Device
+  //      - UUIDs:
+  //         - Generic Access UUID (0x1800)
+  //         - Heart Rate UUID (0x180d)
+  //      - Services:
+  //         - Generic Access Service - Characteristics as described in
+  //           GetGenericAccessService.
+  //         - Heart Rate Service - Characteristics as described in
+  //           GetHeartRateService.
+  //         - Request Disconnection Service - Getting characteristics will

[scheib, 2016/05/19 01:26:57]

It would add to boilerplate test code, but this device would seem more plausible
if e.g. there were a characteristic that when written to caused the disconnect.
It would also make test code a bit more readable: 
 getCharacteristic(kCauseDisconnectCharacteristicUUID)
 .then(char -> char.writeValue 

[Jeffrey Yasskin, 2016/05/19 17:47:07]

Done.

+  //           disconnect the device.
+  static scoped_refptr<testing::NiceMock<device::MockBluetoothAdapter>>
+  GetDisconnectingHeartRateAdapter();
+
   // |BlacklistTestAdapter|
   // Inherits from |EmptyAdapter|
   // Internal Structure: