Add VideoCodec::PreferDecodeLate

The purpose is so that a decoder (Android) that only have a limited number of output buffers can make sure that decoding is done just before the frame is needed.

Removed unused iSupportsRenderTiming and the settings structs since it was not used.
Added VCMReceiver::FrameForDecoding unit test for the case when PreferDecodeLate is set.

Note that this does not change the current behaviour. We actually currently always decode frames late. This cl is to make sure the behaviour is kept for Android, if the default behaviour is changed.

Review URL: https://codereview.webrtc.org/1428293003

Cr-Commit-Position: refs/heads/master@{#10974}

webrtc/modules/video_coding/video_coding_impl.cc

@@ -197,10 +197,8 @@ class VideoCodingModuleImpl : public VideoCodingModule {
   }
 
   void RegisterExternalDecoder(VideoDecoder* externalDecoder,
-                               uint8_t payloadType,
-                               bool internalRenderTiming) override {
-    receiver_.RegisterExternalDecoder(externalDecoder, payloadType,
-                                      internalRenderTiming);
+                               uint8_t payloadType) override {
+    receiver_.RegisterExternalDecoder(externalDecoder, payloadType);
   }
 
   int32_t RegisterReceiveCallback(