Add USB MIC in case of AUDIO_SOURCE_CAMCORDER

A device which supports USB camera cannot record audio stream
because there is no definition of USB audio input device when
specifying CAMCORDER. For getting audio from USB camera,
AUDIO_DEVICE_IN_USB_DEVICE should be added as an audio input device
in case of CAMCORDER.

Test: run cts -m CtsCameraTestCases
Change-Id: I47140a4ae3c6a8c1b5ee1d4b302c97d860cb18d6
diff --git a/services/audiopolicy/enginedefault/src/Engine.cpp b/services/audiopolicy/enginedefault/src/Engine.cpp
index 43205a2..704fc72 100644
--- a/services/audiopolicy/enginedefault/src/Engine.cpp
+++ b/services/audiopolicy/enginedefault/src/Engine.cpp
@@ -680,6 +680,9 @@
             device = AUDIO_DEVICE_IN_BACK_MIC;
         } else if (availableDeviceTypes & AUDIO_DEVICE_IN_BUILTIN_MIC) {
             device = AUDIO_DEVICE_IN_BUILTIN_MIC;
+        } else if (availableDeviceTypes & AUDIO_DEVICE_IN_USB_DEVICE) {
+            // This is specifically for a device without built-in mic
+            device = AUDIO_DEVICE_IN_USB_DEVICE;
         }
         break;
     case AUDIO_SOURCE_VOICE_DOWNLINK: