[PPAPI][MediaStream] Support configure for video input.

ppapi/shared_impl/media_stream_buffer_manager.cc

 // Copyright 2014 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.
 
 #include "ppapi/shared_impl/media_stream_buffer_manager.h"
 
 #include "base/logging.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/shared_impl/media_stream_buffer.h"
 
@@ skipping 13 matching lines @@
 
 MediaStreamBufferManager::~MediaStreamBufferManager() {
 }
 
 bool MediaStreamBufferManager::SetBuffers(
     int32_t number_of_buffers,
     int32_t buffer_size,
     scoped_ptr<base::SharedMemory> shm,
     bool enqueue_all_buffers) {
   DCHECK(shm);
-  DCHECK(!shm_);
   DCHECK_GT(number_of_buffers, 0);
   DCHECK_GT(buffer_size,
             static_cast<int32_t>(sizeof(MediaStreamBuffer::Header)));
   DCHECK_EQ(buffer_size & 0x3, 0);
 
   number_of_buffers_ = number_of_buffers;
   buffer_size_ = buffer_size;
 
   int32_t size = number_of_buffers_ * buffer_size;
   shm_ = shm.Pass();
@@ skipping 26 matching lines @@
 }
 
 MediaStreamBuffer* MediaStreamBufferManager::GetBufferPointer(
     int32_t index) {
   DCHECK_GE(index, 0);
   DCHECK_LT(index, number_of_buffers_);
   return buffers_[index];
 }
 
 }  // namespace ppapi