Make MediaCodecEncoder fallback to a software encoder on failure.

webrtc/video_encoder.h

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 65 matching lines @@
 class VideoEncoder {
  public:
   enum EncoderType {
     kH264,
     kVp8,
     kVp9,
     kUnsupportedCodec,
   };
 
   static VideoEncoder* Create(EncoderType codec_type);
+  // Returns true if this type of encoder can be created using
+  // VideoEncoder::Create.
+  static bool IsSupported(EncoderType codec_type);
 
   static VideoCodecVP8 GetDefaultVp8Settings();
   static VideoCodecVP9 GetDefaultVp9Settings();
   static VideoCodecH264 GetDefaultH264Settings();
 
   virtual ~VideoEncoder() {}
 
   // Initialize the encoder with the information from the codecSettings
   //
   // Input:
@@ skipping 116 matching lines @@
 
   const EncoderType encoder_type_;
   webrtc::VideoEncoder* const encoder_;
 
   std::unique_ptr<webrtc::VideoEncoder> fallback_encoder_;
   std::string fallback_implementation_name_;
   EncodedImageCallback* callback_;
 };
 }  // namespace webrtc
 #endif  // WEBRTC_VIDEO_ENCODER_H_