Bug 1302453 - part1 : send new gecko event when media is resumed. r=baku

We uses "media-playback" event to notify fennec media control about media start
and end. However, if we resume media which was paused by media control, it won't
send any notification to JAVA side so that the MediaControlService can't change
the correct playing icon.

Therefore, we create new event to inform this situation.

MozReview-Commit-ID: zScaHxvHXM

dom/html/HTMLMediaElement.cpp

@@ -37,6 +37,8 @@
 #include "nsContentUtils.h"
 #include "nsIRequest.h"
 #include "nsQueryObject.h"
+#include "nsIObserverService.h"
+#include "nsISupportsPrimitives.h"
 
 #include "nsIScriptSecurityManager.h"
 #include "nsIXPConnect.h"
@@ -5945,6 +5947,7 @@ HTMLMediaElement::SetAudioChannelSuspended(SuspendTypes aSuspend)
     return;
   }
 
+  MaybeNotifyMediaResumed(aSuspend);
   mAudioChannelSuspended = aSuspend;
   MOZ_LOG(AudioChannelService::GetAudioChannelLog(), LogLevel::Debug,
          ("HTMLMediaElement, SetAudioChannelSuspended, this = %p, "
@@ -6427,6 +6430,37 @@ HTMLMediaElement::IsAudible() const
   return true;
 }
 
+void
+HTMLMediaElement::MaybeNotifyMediaResumed(SuspendTypes aSuspend)
+{
+  // In fennec, we should send the notification when media is resumed from the
+  // pause-disposable which was called by media control.
+  if (mAudioChannelSuspended != nsISuspendedTypes::SUSPENDED_PAUSE_DISPOSABLE &&
+      aSuspend != nsISuspendedTypes::NONE_SUSPENDED) {
+    return;
+  }
+
+  uint64_t windowID = mAudioChannelAgent->WindowID();
+  NS_DispatchToMainThread(NS_NewRunnableFunction([windowID]() -> void {
+    nsCOMPtr<nsIObserverService> observerService =
+      services::GetObserverService();
+    if (NS_WARN_IF(!observerService)) {
+      return;
+    }
+
+    nsCOMPtr<nsISupportsPRUint64> wrapper =
+      do_CreateInstance(NS_SUPPORTS_PRUINT64_CONTRACTID);
+    if (NS_WARN_IF(!wrapper)) {
+       return;
+    }
+
+    wrapper->SetData(windowID);
+    observerService->NotifyObservers(wrapper,
+                                     "media-playback-resumed",
+                                     u"active");
+  }));
+}
+
 bool
 HTMLMediaElement::HaveFailedWithSourceNotSupportedError() const
 {