VideoFrameBuffer: Make non-const data access explicit

webrtc/common_video/i420_buffer_pool.cc

 /*
  *  Copyright (c) 2015 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.
  */
 
 #include "webrtc/common_video/interface/i420_buffer_pool.h"
 
 #include "webrtc/base/checks.h"
 
 namespace {
 
 // One extra indirection is needed to make |HasOneRef| work.
 class PooledI420Buffer : public webrtc::VideoFrameBuffer {
  public:
   explicit PooledI420Buffer(
       const rtc::scoped_refptr<webrtc::I420Buffer>& buffer)
       : buffer_(buffer) {}
 
  private:
   ~PooledI420Buffer() override {}
 
   int width() const override { return buffer_->width(); }
   int height() const override { return buffer_->height(); }
   const uint8_t* data(webrtc::PlaneType type) const override {
-    const webrtc::I420Buffer* cbuffer = buffer_.get();
-    return cbuffer->data(type);
+    return buffer_->data(type);
   }
-  uint8_t* data(webrtc::PlaneType type) {
+  uint8_t* MutableData(webrtc::PlaneType type) override {
+    // Make the HasOneRef() check here instead of in |buffer_|, because the pool
+    // also has a reference to |buffer_|.
     DCHECK(HasOneRef());
-    const webrtc::I420Buffer* cbuffer = buffer_.get();
-    return const_cast<uint8_t*>(cbuffer->data(type));
+    return const_cast<uint8_t*>(buffer_->data(type));
   }
   int stride(webrtc::PlaneType type) const override {
     return buffer_->stride(type);
   }
   void* native_handle() const override { return nullptr; }
 
   rtc::scoped_refptr<VideoFrameBuffer> NativeToI420Buffer() override {
     RTC_NOTREACHED();
     return nullptr;
   }
@@ skipping 34 matching lines @@
     // and it's safe to reuse.
     if (buffer->HasOneRef())
       return new rtc::RefCountedObject<PooledI420Buffer>(buffer);
   }
   // Allocate new buffer.
   buffers_.push_back(new rtc::RefCountedObject<I420Buffer>(width, height));
   return new rtc::RefCountedObject<PooledI420Buffer>(buffers_.back());
 }
 
 }  // namespace webrtc