Delete IsMutable and IsExclusive methods.

webrtc/common_video/video_frame_buffer.cc

Index: webrtc/common_video/video_frame_buffer.cc
diff --git a/webrtc/common_video/video_frame_buffer.cc b/webrtc/common_video/video_frame_buffer.cc
index 700dcaf02b7af098798eb51e344f065b232a8700..34213e4656ce766f5cb6f2fdc24e566c02cf152e 100644
--- a/webrtc/common_video/video_frame_buffer.cc
+++ b/webrtc/common_video/video_frame_buffer.cc
@@ -154,20 +154,13 @@ const uint8_t* I420Buffer::DataV() const {
   return data_.get() + stride_y_ * height_ + stride_u_ * ((height_ + 1) / 2);
 }
 
-bool I420Buffer::IsMutable() {
-  return HasOneRef();
-}
-
 uint8_t* I420Buffer::MutableDataY() {
-  RTC_DCHECK(IsMutable());
   return const_cast<uint8_t*>(DataY());
 }
 uint8_t* I420Buffer::MutableDataU() {
-  RTC_DCHECK(IsMutable());
   return const_cast<uint8_t*>(DataU());
 }
 uint8_t* I420Buffer::MutableDataV() {
-  RTC_DCHECK(IsMutable());
   return const_cast<uint8_t*>(DataV());
 }
 
@@ -216,10 +209,6 @@ NativeHandleBuffer::NativeHandleBuffer(void* native_handle,
   RTC_DCHECK_GT(height, 0);
 }
 
-bool NativeHandleBuffer::IsMutable() {
-  return false;
-}
-
 int NativeHandleBuffer::width() const {
   return width_;
 }
@@ -282,11 +271,6 @@ WrappedI420Buffer::~WrappedI420Buffer() {
   no_longer_used_cb_();
 }
 
-// Data owned by creator; never mutable.
-bool WrappedI420Buffer::IsMutable() {
-  return false;
-}
-
 int WrappedI420Buffer::width() const {
   return width_;
 }