Bug 1369108 - 3. Implement new device permission code path for Fennec; r=esawin

Instead of asking for permission in VideoCaptureDeviceInfoAndroid.java,
we now merely check for permission there. The actual permission prompt
now happens in WebrtcUI.js, using the new
"getUserMedia:ask-device-permission" and
"getUserMedia:got-device-permission" notifications.

MozReview-Commit-ID: DSVPjjW2JNR

media/webrtc/trunk/webrtc/modules/video_capture/android/java/src/org/webrtc/videoengine/VideoCaptureDeviceInfoAndroid.java

@@ -75,8 +75,8 @@ public class VideoCaptureDeviceInfoAndroid {
   // marked "private" as it is only called by native code.
   @WebRTCJNITarget
   private static CaptureCapabilityAndroid[] getDeviceInfo() {
-      final boolean hasPermissions = Permissions.waitFor(
-              (Activity) GeckoAppShell.getContext(), Manifest.permission.CAMERA);
+      final boolean hasPermissions = Permissions.has(
+              GeckoAppShell.getApplicationContext(), Manifest.permission.CAMERA);
 
       if (hasPermissions) {
           return createDeviceList();

mobile/android/app/mobile.js

@@ -924,3 +924,6 @@ pref("dom.keyboardevent.dispatch_during_composition", true);
 #if CPU_ARCH == aarch64
 pref("javascript.options.native_regexp", false);
 #endif
+
+// Ask for permission when enumerating WebRTC devices.
+pref("media.navigator.permission.device", true);

mobile/android/chrome/content/WebrtcUI.js

@@ -28,9 +28,15 @@ var WebrtcUI = {
   // See browser/modules/webrtcUI.jsm for details.
 
   observe: function(aSubject, aTopic, aData) {
-    if (aTopic === "getUserMedia:request") {
+    if (aTopic === "getUserMedia:ask-device-permission") {
       RuntimePermissions
-        .waitForPermissions(this._determineNeededRuntimePermissions(aSubject))
+        .waitForPermissions(this._determineNeededRuntimePermissions(aData))
+        .then(_ => {
+          Services.obs.notifyObservers(aSubject, "getUserMedia:got-device-permission");
+        });
+    } else if (aTopic === "getUserMedia:request") {
+      RuntimePermissions
+        .checkPermissions(this._determineNeededRuntimePermissions(aSubject))
         .then((permissionGranted) => {
           if (permissionGranted) {
             WebrtcUI.handleGumRequest(aSubject, aTopic, aData);
@@ -178,7 +184,16 @@ var WebrtcUI = {
   _determineNeededRuntimePermissions: function(aSubject) {
     let permissions = [];
 
-    let constraints = aSubject.getConstraints();
+    let constraints;
+    if (typeof aSubject === "string") {
+      constraints = {
+        video: aSubject === "video" || aSubject === "all",
+        audio: aSubject === "audio" || aSubject === "all",
+      };
+    } else {
+      constraints = aSubject.getConstraints();
+    }
+
     if (constraints.video) {
       permissions.push(RuntimePermissions.CAMERA);
     }

mobile/android/chrome/content/browser.js

@@ -159,7 +159,8 @@ var lazilyLoadedObserverScripts = [
 
 if (AppConstants.MOZ_WEBRTC) {
   lazilyLoadedObserverScripts.push(
-    ["WebrtcUI", ["getUserMedia:request",
+    ["WebrtcUI", ["getUserMedia:ask-device-permission",
+                  "getUserMedia:request",
                   "PeerConnection:request",
                   "recording-device-events",
                   "VideoCapture:Paused",