Revert of Introduce an IsMutable method on VideoFrameBuffer.

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.
  */
 
@@ skipping 11 matching lines @@
       : 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 {
     return buffer_->data(type);
   }
-  bool IsMutable() { return HasOneRef(); }
   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_|.
-    RTC_DCHECK(IsMutable());
+    RTC_DCHECK(HasOneRef());
     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 27 matching lines @@
     else
       ++it;
   }
   // Look for a free buffer.
   for (const rtc::scoped_refptr<I420Buffer>& buffer : buffers_) {
     // If the buffer is in use, the ref count will be 2, one from the list we
     // are looping over and one from a PooledI420Buffer returned from
     // CreateBuffer that has not been released yet. If the ref count is 1
     // (HasOneRef), then the list we are looping over holds the only reference
     // and it's safe to reuse.
-    if (buffer->IsMutable())
+    if (buffer->HasOneRef())
       return new rtc::RefCountedObject<PooledI420Buffer>(buffer);
   }
   // Allocate new buffer.
   rtc::scoped_refptr<I420Buffer> buffer = new rtc::RefCountedObject<I420Buffer>(
       width, height);
   if (zero_initialize_)
     buffer->InitializeData();
   buffers_.push_back(buffer);
   return new rtc::RefCountedObject<PooledI420Buffer>(buffers_.back());
 }
 
 }  // namespace webrtc