Don't build EME-specific subroutines without EME.

- Checks for restricted or encrypted content
- Dispatching 'encrypted' events
- Dispatching 'key needed' events
- HTML Media Element media keys system
- EME telemetry
- HTML Media Element EME API

This is the main bulk for #26, isolating EME-specific code.

dom/media/mediasource/TrackBuffersManager.cpp

@@ -58,6 +58,7 @@ AppendStateToStr(SourceBufferAttributes::AppendState aState)
 
 static Atomic<uint32_t> sStreamSourceID(0u);
 
+#ifdef MOZ_EME
 class DispatchKeyNeededEvent : public Runnable {
 public:
   DispatchKeyNeededEvent(AbstractMediaDecoder* aDecoder,
@@ -83,6 +84,7 @@ private:
   nsTArray<uint8_t> mInitData;
   nsString mInitDataType;
 };
+#endif
 
 TrackBuffersManager::TrackBuffersManager(MediaSourceDecoder* aParentDecoder,
                                          const nsACString& aType)
@@ -1097,12 +1099,14 @@ TrackBuffersManager::OnDemuxerInitDone(nsresult)
 
   UniquePtr<EncryptionInfo> crypto = mInputDemuxer->GetCrypto();
   if (crypto && crypto->IsEncrypted()) {
+#ifdef MOZ_EME
     // Try and dispatch 'encrypted'. Won't go if ready state still HAVE_NOTHING.
     for (uint32_t i = 0; i < crypto->mInitDatas.Length(); i++) {
       NS_DispatchToMainThread(
         new DispatchKeyNeededEvent(mParentDecoder, crypto->mInitDatas[i].mInitData,
                                    crypto->mInitDatas[i].mType));
     }
+#endif
     info.mCrypto = *crypto;
     // We clear our crypto init data array, so the MediaFormatReader will
     // not emit an encrypted event for the same init data again.