Simplify VCMTimestampMap.

webrtc/modules/video_coding/main/source/generic_decoder.cc

Index: webrtc/modules/video_coding/main/source/generic_decoder.cc
diff --git a/webrtc/modules/video_coding/main/source/generic_decoder.cc b/webrtc/modules/video_coding/main/source/generic_decoder.cc
index 1cd67dfddfbb2a176bcfb48dc697e58cbeb83a30..f874e163c83f6ad3a3362cefe32a014f23585059 100644
--- a/webrtc/modules/video_coding/main/source/generic_decoder.cc
+++ b/webrtc/modules/video_coding/main/source/generic_decoder.cc
@@ -53,8 +53,7 @@ int32_t VCMDecodedFrameCallback::Decoded(VideoFrame& decodedImage) {
     VCMReceiveCallback* callback;
     {
         CriticalSectionScoped cs(_critSect);
-        frameInfo = static_cast<VCMFrameInformation*>(
-            _timestampMap.Pop(decodedImage.timestamp()));
+        frameInfo = _timestampMap.Pop(decodedImage.timestamp());
         callback = _receiveCallback;
     }
 
@@ -103,10 +102,10 @@ uint64_t VCMDecodedFrameCallback::LastReceivedPictureID() const
     return _lastReceivedPictureID;
 }
 
-int32_t VCMDecodedFrameCallback::Map(uint32_t timestamp, VCMFrameInformation* frameInfo)
-{
-    CriticalSectionScoped cs(_critSect);
-    return _timestampMap.Add(timestamp, frameInfo);
+void VCMDecodedFrameCallback::Map(uint32_t timestamp,
+                                  VCMFrameInformation* frameInfo) {
+  CriticalSectionScoped cs(_critSect);
+  _timestampMap.Add(timestamp, frameInfo);
 }
 
 int32_t VCMDecodedFrameCallback::Pop(uint32_t timestamp)