audio: add reporting of gapless playback support

Add reporting of gapless playback support via
getOffloadSupport() method which replaces isOffloadSupported().
The audio HAL implementation indicates gapless support by setting flag
AUDIO_OUTPUT_FLAG_GAPLESS_OFFLOAD on an output profile in addition to
flag AUDIO_OUTPUT_FLAG_COMPRESS_OFFLOAD.

Bug: 158191844
Test: make
Change-Id: I7a8fa284c2486fd7a74782acb1ac7537d1534e49
diff --git a/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp b/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
index df8e4c5..e9271a7 100644
--- a/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
+++ b/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
@@ -1086,15 +1086,15 @@
     return mAudioPolicyManager->setAllowedCapturePolicy(uid, capturePolicy);
 }
 
-bool AudioPolicyService::isOffloadSupported(const audio_offload_info_t& info)
+audio_offload_mode_t AudioPolicyService::getOffloadSupport(const audio_offload_info_t& info)
 {
     if (mAudioPolicyManager == NULL) {
         ALOGV("mAudioPolicyManager == NULL");
-        return false;
+        return AUDIO_OFFLOAD_NOT_SUPPORTED;
     }
     Mutex::Autolock _l(mLock);
     AutoCallerClear acc;
-    return mAudioPolicyManager->isOffloadSupported(info);
+    return mAudioPolicyManager->getOffloadSupport(info);
 }
 
 bool AudioPolicyService::isDirectOutputSupported(const audio_config_base_t& config,