--- a/dom/media/MediaDecoderOwner.h
+++ b/dom/media/MediaDecoderOwner.h
@@ -36,26 +36,16 @@ public:
   /**
    * Fires a timeupdate event. If aPeriodic is true, the event will only
    * be fired if we've not fired a timeupdate event (for any reason) in the
    * last 250ms, as required by the spec when the current time is periodically
    * increasing during playback.
    */
   virtual void FireTimeUpdate(bool aPeriodic) = 0;
 
-  // Get the HTMLMediaElement object if the decoder is being used from an
-  // HTML media element, and null otherwise.
-  virtual dom::HTMLMediaElement* GetMediaElement()
-  {
-    return nullptr;
-  }
-
-  // Return an abstract thread on which to run main thread runnables.
-  virtual AbstractThread* AbstractMainThread() const = 0;
-
   // Return true if decoding should be paused
   virtual bool GetPaused() = 0;
 
   // Called by the video decoder object, on the main thread,
   // when it has read the metadata containing video dimensions,
   // etc.
   // Must take ownership of MetadataTags aTags argument.
   virtual void MetadataLoaded(const MediaInfo* aInfo,
@@ -138,55 +128,74 @@ public:
   };
 
   // Check if the decoder owner is active.
   virtual bool IsActive() const = 0;
 
   // Check if the decoder owner is hidden.
   virtual bool IsHidden() const = 0;
 
-  // Called by the media decoder and the video frame to get the
-  // ImageContainer containing the video data.
-  virtual VideoFrameContainer* GetVideoFrameContainer() = 0;
-
   // Called by media decoder when the audible state changed
   virtual void SetAudibleState(bool aAudible) = 0;
 
   // Notified by the decoder that XPCOM shutdown has begun.
   // The decoder owner should call Shutdown() on the decoder and drop the
   // reference to the decoder to prevent further calls into the decoder.
   virtual void NotifyXPCOMShutdown() = 0;
 
   // Dispatches a "encrypted" event to the HTMLMediaElement, with the
   // provided init data. Actual dispatch may be delayed until HAVE_METADATA.
   // 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;
-
   // Called by the media decoder to create audio/video tracks and add to its
   // owner's track list.
   virtual void ConstructMediaTracks(const MediaInfo* aInfo) = 0;
 
   // Called by the media decoder to removes all audio/video tracks from its
   // owner's track list.
   virtual void RemoveMediaTracks() = 0;
 
-  // Called by the media decoder to create a GMPCrashHelper.
-  virtual already_AddRefed<GMPCrashHelper> CreateGMPCrashHelper() = 0;
-
   // Called by the media decoder to notify the owner to resolve a seek promise.
   virtual void AsyncResolveSeekDOMPromiseIfExists() = 0;
 
   // Called by the media decoder to notify the owner to reject a seek promise.
   virtual void AsyncRejectSeekDOMPromiseIfExists() = 0;
 
   // Notified by the decoder that a decryption key is required before emitting
   // further output.
   virtual void NotifyWaitingForKey() {}
+
+  /*
+   * Methods that are used only in Gecko go here. We provide defaul
+   * implementations so they can compile in Servo without modification.
+   */
+  // Return an abstract thread on which to run main thread runnables.
+  virtual AbstractThread* AbstractMainThread() const { return nullptr; }
+
+  // Get the HTMLMediaElement object if the decoder is being used from an
+  // HTML media element, and null otherwise.
+  virtual dom::HTMLMediaElement* GetMediaElement() { return nullptr; }
+
+  // Called by the media decoder and the video frame to get the
+  // ImageContainer containing the video data.
+  virtual VideoFrameContainer* GetVideoFrameContainer() { return nullptr; }
+
+  // Return the decoder owner's owner document.
+  virtual nsIDocument* GetDocument() const { return nullptr; }
+
+  // Called by the media decoder to create a GMPCrashHelper.
+  virtual already_AddRefed<GMPCrashHelper> CreateGMPCrashHelper()
+  {
+    return nullptr;
+  }
+
+  /*
+   * Servo only methods go here. Please provide default implementations so they
+   * can build in Gecko without any modification.
+   */
 };
 
 } // namespace mozilla
 
 #endif
 

--- a/dom/media/gtest/MockMediaDecoderOwner.h
+++ b/dom/media/gtest/MockMediaDecoderOwner.h
@@ -37,29 +37,23 @@ public:
   void DispatchEncrypted(const nsTArray<uint8_t>& aInitData,
                          const nsAString& aInitDataType) override {}
   bool IsActive() const override { return true; }
   bool IsHidden() const override { return false; }
   void DownloadSuspended() override {}
   void DownloadResumed(bool aForceNetworkLoading) override {}
   void NotifySuspendedByCache(bool aIsSuspended) override {}
   void NotifyDecoderPrincipalChanged() override {}
-  VideoFrameContainer* GetVideoFrameContainer() override
-  {
-    return nullptr;
-  }
   void SetAudibleState(bool aAudible) override {}
   void NotifyXPCOMShutdown() override {}
   AbstractThread* AbstractMainThread() const override
   {
     // Non-DocGroup version for Mock.
     return AbstractThread::MainThread();
   }
-  nsIDocument* GetDocument() const { return nullptr; }
   void ConstructMediaTracks(const MediaInfo* aInfo) {}
   void RemoveMediaTracks() {}
-  already_AddRefed<GMPCrashHelper> CreateGMPCrashHelper() { return nullptr; }
   void AsyncResolveSeekDOMPromiseIfExists() override {}
   void AsyncRejectSeekDOMPromiseIfExists() override {}
 };
 }
 
 #endif