Bug 1288980 - Add libcubeb backend to about:support. r=felipc

dom/base/nsDOMWindowUtils.cpp

@@ -30,6 +30,7 @@
 #ifdef MOZ_FMP4
 #include "MP4Decoder.h"
 #endif
+#include "CubebUtils.h"
 
 #include "nsIScrollableFrame.h"
 
@@ -2326,6 +2327,13 @@ nsDOMWindowUtils::GetSupportsHardwareH264Decoding(JS::MutableHandle<JS::Value> a
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsDOMWindowUtils::GetCurrentAudioBackend(nsAString& aBackend)
+{
+  CubebUtils::GetCurrentBackend(aBackend);
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsDOMWindowUtils::StartFrameTimeRecording(uint32_t *startIndex)
 {

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -1400,6 +1400,11 @@ interface nsIDOMWindowUtils : nsISupports {
    */
   readonly attribute jsval supportsHardwareH264Decoding;
 
+  /**
+   * Returns the current audio backend as a free-form string.
+   */
+  readonly attribute AString currentAudioBackend;
+
   /**
    * Record (and return) frame-intervals for frames which were presented
    *   between calling StartFrameTimeRecording and StopFrameTimeRecording.

dom/media/CubebUtils.cpp

@@ -296,5 +296,15 @@ cubeb_stream_type ConvertChannelToCubebType(dom::AudioChannel aChannel)
 }
 #endif
 
+void GetCurrentBackend(nsAString& aBackend)
+{
+  const char* backend = cubeb_get_backend_id(GetCubebContext());
+  if (!backend) {
+    aBackend.AssignLiteral("unknown");
+    return;
+  }
+  aBackend.AssignASCII(backend);
+}
+
 } // namespace CubebUtils
 } // namespace mozilla

dom/media/CubebUtils.h

@@ -46,6 +46,7 @@ bool CubebLatencyPrefSet();
 #if defined(__ANDROID__) && defined(MOZ_B2G)
 cubeb_stream_type ConvertChannelToCubebType(dom::AudioChannel aChannel);
 #endif
+void GetCurrentBackend(nsAString& aBackend);
 
 } // namespace CubebUtils
 } // namespace mozilla

toolkit/content/aboutSupport.js

@@ -368,6 +368,7 @@ var snapshotFormatters = {
     addRowFromKey("features", "webglRenderer");
     addRowFromKey("features", "webgl2Renderer");
     addRowFromKey("features", "supportsHardwareH264", "hardwareH264");
+    addRowFromKey("features", "currentAudioBackend", "audioBackend");
     addRowFromKey("features", "direct2DEnabled", "#Direct2D");
 
     if ("directWriteEnabled" in data) {

toolkit/locales/en-US/chrome/global/aboutSupport.properties

@@ -57,6 +57,7 @@ clearTypeParameters = ClearType Parameters
 
 compositing = Compositing
 hardwareH264 = Hardware H264 Decoding
+audioBackend = Audio Backend
 mainThreadNoOMTC = main thread, no OMTC
 yes = Yes
 no = No

toolkit/modules/Troubleshoot.jsm

@@ -367,6 +367,8 @@ var dataProviders = {
     });
     promises.push(promise);
 
+    data.currentAudioBackend = winUtils.currentAudioBackend;
+
     if (!data.numAcceleratedWindows && gfxInfo) {
       let win = AppConstants.platform == "win";
       let feature = win ? gfxInfo.FEATURE_DIRECT3D_9_LAYERS :

toolkit/modules/tests/browser/browser_Troubleshoot.js

@@ -228,6 +228,9 @@ const SNAPSHOT_SCHEMA = {
         supportsHardwareH264: {
           type: "string",
         },
+        currentAudioBackend: {
+          type: "string",
+        },
         numAcceleratedWindowsMessage: {
           type: "array",
         },