[GCM] Investigatory CHECKs for crash in parsing stream

google_apis/gcm/base/socket_stream.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Protobuf ZeroCopy[Input/Output]Stream implementations capable of using a
 // net::StreamSocket. Built to work with Protobuf CodedStreams.
 
 #ifndef GOOGLE_APIS_GCM_BASE_SOCKET_STREAM_H_
 #define GOOGLE_APIS_GCM_BASE_SOCKET_STREAM_H_
 
@@ skipping 54 matching lines @@
   explicit SocketInputStream(net::StreamSocket* socket);
   virtual ~SocketInputStream();
 
   // ZeroCopyInputStream implementation.
   virtual bool Next(const void** data, int* size) OVERRIDE;
   virtual void BackUp(int count) OVERRIDE;
   virtual bool Skip(int count) OVERRIDE;  // Not implemented.
   virtual int64 ByteCount() const OVERRIDE;
 
   // The remaining amount of valid data available to be read.
-  size_t UnreadByteCount() const;
+  int UnreadByteCount() const;
 
   // Reads from the socket, appending a max of |byte_limit| bytes onto the read
   // buffer. net::ERR_IO_PENDING is returned if the refresh can't complete
   // synchronously, in which case the callback is invoked upon completion. If
   // the refresh can complete synchronously, even in case of an error, returns
   // net::OK without invoking callback.
   // Note: GetState() (and possibly last_error()) should be checked upon
   // completion to determine whether the Refresh encountered an error.
   net::Error Refresh(const base::Closure& callback, int byte_limit);
 
@@ skipping 110 matching lines @@
   net::Error last_error_;
 
   base::WeakPtrFactory<SocketOutputStream> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SocketOutputStream);
 };
 
 }  // namespace gcm
 
 #endif  // GOOGLE_APIS_GCM_BASE_SOCKET_STREAM_H_