Adding more comments to every header file in api/ subdirectory.

webrtc/api/proxy.h

 /*
  *  Copyright 2013 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.
  */
 
 // This file contains Macros for creating proxies for webrtc MediaStream and
 // PeerConnection classes.
+// TODO(deadbeef): Move this to pc/; this is part of the implementation.
 
 //
 // Example usage:
 //
 // class TestInterface : public rtc::RefCountInterface {
 //  public:
 //   std::string FooA() = 0;
 //   std::string FooB(bool arg1) const = 0;
 //   std::string FooC(bool arg1) = 0;
 //  };
@@ skipping 527 matching lines @@
 #define PROXY_WORKER_CONSTMETHOD2(r, method, t1, t2)                         \
   r method(t1 a1, t2 a2) const override {                                    \
     ConstMethodCall2<C, r, t1, t2> call(c_.get(), &C::method, std::move(a1), \
                                         std::move(a2));                      \
     return call.Marshal(RTC_FROM_HERE, worker_thread_);                      \
   }
 
 }  // namespace webrtc
 
 #endif  //  WEBRTC_API_PROXY_H_