Bug 1347402 part 2 - open a GetOwnerDoc() interface at the MediaDecoderOwner; r=jwwang

Open a GetOwnerDoc() method to the MediaDecoderOwner interface and then we can get the
owner document via a pointer to MediaDecoderOwner in MediaDecoder.

MozReview-Commit-ID: JCzQDLx1MsU

--HG--
extra : rebase_source : e194c95cb1513046ec7aa19d6c6e9f8231971a2d
extra : source : 1b9c45911a036e3677b6636cda84a636681d71de

dom/html/HTMLMediaElement.cpp

@@ -7410,6 +7410,12 @@ HTMLMediaElement::NotifyDecoderActivityChanges() const
   }
 }
 
+nsIDocument*
+HTMLMediaElement::GetDocument() const
+{
+  return OwnerDoc();
+}
+
 bool HasDebuggerPrivilege(JSContext* aCx, JSObject* aObj)
 {
   return nsContentUtils::CallerHasPermission(aCx,

dom/html/HTMLMediaElement.h

@@ -774,6 +774,8 @@ public:
   };
   void MarkAsContentSource(CallerAPI aAPI);
 
+  nsIDocument* GetDocument() const override;
+
 protected:
   virtual ~HTMLMediaElement();
 

dom/media/MediaDecoderOwner.h

@@ -157,6 +157,9 @@ public:
   // Main thread only.
   virtual void DispatchEncrypted(const nsTArray<uint8_t>& aInitData,
                                  const nsAString& aInitDataType) = 0;
+
+  // Return the decoder owner's owner document.
+  virtual nsIDocument* GetDocument() const = 0;
 };
 
 } // namespace mozilla

dom/media/gtest/MockMediaDecoderOwner.h

@@ -54,6 +54,7 @@ public:
     // Non-DocGroup version for Mock.
     return AbstractThread::MainThread();
   }
+  nsIDocument* GetDocument() const { return nullptr; }
 };
 }