Fix webrtcAudioPrivate API to handle requests from <webview>s.

chrome/common/extensions/api/webrtc_audio_private.idl

Index: chrome/common/extensions/api/webrtc_audio_private.idl
diff --git a/chrome/common/extensions/api/webrtc_audio_private.idl b/chrome/common/extensions/api/webrtc_audio_private.idl
index e4b7c86a3e0437e202bcb910daabb18798872e0c..32afbd48ee9288b4e4fac6c9807775132584a8e7 100644
--- a/chrome/common/extensions/api/webrtc_audio_private.idl
+++ b/chrome/common/extensions/api/webrtc_audio_private.idl
@@ -4,7 +4,7 @@
 
 // The <code>chrome.webrtcAudioPrivate</code> API allows enumeration
 // of audio output (sink) devices as well as getting and setting the
-// active device for a given tab.
+// active device for a given requesting process.
 //
 // Note that device IDs as used in this API are opaque (i.e. they are
 // not the hardware identifier of the device) and while they are
@@ -41,16 +41,26 @@ namespace webrtcAudioPrivate {
   callback SinkIdCallback = void(DOMString sinkId);
   callback CompletionCallback = void();
 
+  dictionary RequestInfo {
+    // The tab identifier from the chrome.tabs API, if the request is from a
+    // tab.
+    long? tabId;
+    // The guest process id for the requester, if the request is from a
+    // webview.
+    long? guestProcessId;
+  };
+
   interface Functions {
     // Retrieves a list of available audio sink devices.
     static void getSinks(GetSinksCallback callback);
 
-    // Retrieves the currently active audio sink for the given tab.
-    static void getActiveSink(long tabId,
+    // Retrieves the currently active audio sink for the given requesting
+    // process.
+    static void getActiveSink(RequestInfo request,
                               SinkIdCallback callback);
 
-    // Sets the active audio sink device for the specified tab.
-    static void setActiveSink(long tabId,
+    // Sets the active audio sink device for the specified requesting process.
+    static void setActiveSink(RequestInfo request,
                               DOMString sinkId,
                               optional CompletionCallback callback);
 
@@ -60,7 +70,7 @@ namespace webrtcAudioPrivate {
     // sink.
     //
     // The associated sink ID can be used as a sink ID for
-    // setActiveSink. It is valid irrespective of which tab you are
+    // setActiveSink. It is valid irrespective of which process you are
     // setting the active sink for.
     static void getAssociatedSink(DOMString securityOrigin,
                                   DOMString sourceIdInOrigin,