Remaining changes to build all code in src.git with -Wimplicit-fallthrough.

Fixes a bug where device ordinal 5 would fall through to device ordinal 6
after resetting the name, cf
https://codereview.chromium.org/2440043002/diff/120001/device/bluetooth/test/bluetooth_test_bluez.cc

This CL was uploaded by git cl split.

R=ortuno@chromium.org

Bug: 177475
Change-Id: I93fd60b42f634c4b84c464452861f2cf3aa32f37
Reviewed-on: https://chromium-review.googlesource.com/891502
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532871}

device/bluetooth/test/bluetooth_test_bluez.cc

@@ -148,6 +148,7 @@ BluetoothDevice* BluetoothTestBlueZ::SimulateLowEnergyDevice(
       break;
     case 5:
       device_name = base::nullopt;
+      break;
     case 6:
       device_address = kTestDeviceAddress2;
       device_type = BLUETOOTH_TRANSPORT_DUAL;