Bug 1593843 - part10 : ask for the play permission when creating media element. r=bryce

For media element, as the spec requires that we should know the whether it can be allowed to play when we call `media.play()` [1], which means that we should get the result before the play invocation.

Therefore, we request for the play permission when we create media element.

Differential Revision: https://phabricator.services.mozilla.com/D52438

--HG--
extra : moz-landing-system : lando

dom/html/HTMLMediaElement.cpp

@@ -19,6 +19,7 @@
 #include "DecoderTraits.h"
 #include "FrameStatistics.h"
 #include "GMPCrashHelper.h"
+#include "GVAutoplayPermissionRequest.h"
 #ifdef MOZ_ANDROID_HLS_SUPPORT
 #  include "HLSDecoder.h"
 #endif
@@ -4051,6 +4052,11 @@ void HTMLMediaElement::Init() {
   // in JS)
   MediaShutdownManager::InitStatics();
 
+#if defined(MOZ_WIDGET_ANDROID)
+  GVAutoplayPermissionRequestor::AskForPermissionIfNeeded(
+      OwnerDoc()->GetInnerWindow());
+#endif
+
   mShutdownObserver->Subscribe(this);
   mInitialized = true;
 }