Revert following changes for fixing Primetime issue:

- Issue #26 Part 2a: make more EME code conditional. (99118e38e)
- Issue #26 - Part 2b: Stub out GMPDecryptorProxy functions. (d44c61bf6)
- Issue #26 - Part 2c: Remove dependence on gmp/widevine-adapter/* (4c9689f68)
- Issue #1392 - Change --enable-eme to MOZ_ARG_ENABLE_BOOL and remove MOZ_EME_MODULES (832d84d2c)
- [Basilisk] Issue MoonchildProductions/UXP#1392 - Remove usage of MOZ_EME_MODULES (3a165cd)
- Issue #65 - Remove AppConstants from toolkit/mozapps/extensions (758618b60)

dom/media/MediaFormatReader.h

@@ -20,9 +20,7 @@
 
 namespace mozilla {
 
-#ifdef MOZ_EME
 class CDMProxy;
-#endif
 
 class MediaFormatReader final : public MediaDecoderReader
 {
@@ -93,9 +91,7 @@ public:
     return mTrackDemuxersMayBlock;
   }
 
-#ifdef MOZ_EME
   void SetCDMProxy(CDMProxy* aProxy) override;
-#endif
 
   // Returns a string describing the state of the decoder data.
   // Used for debugging purposes.
@@ -588,9 +584,7 @@ private:
   RefPtr<VideoFrameContainer> mVideoFrameContainer;
   layers::ImageContainer* GetImageContainer();
 
-#ifdef MOZ_EME
   RefPtr<CDMProxy> mCDMProxy;
-#endif
 
   RefPtr<GMPCrashHelper> mCrashHelper;