Use mapped memory for uploading large textures.

gpu/command_buffer/client/transfer_buffer.cc

 // Copyright (c) 2012 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.
 
 // A class to Manage a growing transfer buffer.
 
 #include "gpu/command_buffer/client/transfer_buffer.h"
 
 #include "base/bits.h"
 #include "base/logging.h"
@@ skipping 55 matching lines @@
 
 bool TransferBuffer::HaveBuffer() const {
   DCHECK(buffer_id_ == -1 || buffer_.get());
   return buffer_id_ != -1;
 }
 
 RingBuffer::Offset TransferBuffer::GetOffset(void* pointer) const {
   return ring_buffer_->GetOffset(pointer);
 }
 
+void TransferBuffer::DiscardBlock(void* p) {
+  ring_buffer_->DiscardBlock(p);
+}
+
 void TransferBuffer::FreePendingToken(void* p, unsigned int token) {
   ring_buffer_->FreePendingToken(p, token);
   if (bytes_since_last_flush_ >= size_to_flush_ && size_to_flush_ > 0) {
     helper_->Flush();
     bytes_since_last_flush_ = 0;
   }
 }
 
 void TransferBuffer::AllocateRingBuffer(unsigned int size) {
   for (;size >= min_buffer_size_; size /= 2) {
@@ skipping 95 matching lines @@
 }
 
 void ScopedTransferBufferPtr::Release() {
   if (buffer_) {
     transfer_buffer_->FreePendingToken(buffer_, helper_->InsertToken());
     buffer_ = NULL;
     size_ = 0;
   }
 }
 
+void ScopedTransferBufferPtr::Discard() {
+  if (buffer_) {
+    transfer_buffer_->DiscardBlock(buffer_);
+    buffer_ = NULL;
+    size_ = 0;
+  }
+}
+
 void ScopedTransferBufferPtr::Reset(unsigned int new_size) {
   Release();
   // NOTE: we allocate buffers of size 0 so that HaveBuffer will be true, so
   // that address will return a pointer just like malloc, and so that GetShmId
   // will be valid. That has the side effect that we'll insert a token on free.
   // We could add code skip the token for a zero size buffer but it doesn't seem
   // worth the complication.
   buffer_ = transfer_buffer_->AllocUpTo(new_size, &size_);
 }
 
 }  // namespace gpu