services/ui: Implement MojoGpuMemoryBufferManager::CreateGpuMemoryBufferFromHandle

services/ui/public/cpp/mojo_gpu_memory_buffer.cc

 // Copyright 2015 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 "services/ui/public/cpp/mojo_gpu_memory_buffer.h"
 
 #include <stdint.h>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/shared_memory.h"
 #include "base/numerics/safe_conversions.h"
 #include "build/build_config.h"
 #include "mojo/public/cpp/system/buffer.h"
 #include "mojo/public/cpp/system/platform_handle.h"
 #include "ui/gfx/buffer_format_util.h"
 
 namespace ui {
 
 MojoGpuMemoryBufferImpl::MojoGpuMemoryBufferImpl(
     const gfx::Size& size,
     gfx::BufferFormat format,
     std::unique_ptr<base::SharedMemory> shared_memory)
     : GpuMemoryBufferImpl(gfx::GenericSharedMemoryId(0), size, format),
       shared_memory_(std::move(shared_memory)) {}
 
 // TODO(rjkroege): Support running a destructor callback as necessary.
 MojoGpuMemoryBufferImpl::~MojoGpuMemoryBufferImpl() {}
 
+// static
 std::unique_ptr<gfx::GpuMemoryBuffer> MojoGpuMemoryBufferImpl::Create(
     const gfx::Size& size,
     gfx::BufferFormat format,
     gfx::BufferUsage usage) {
   size_t bytes = gfx::BufferSizeForBufferFormat(size, format);
 
   mojo::ScopedSharedBufferHandle handle =
       mojo::SharedBufferHandle::Create(bytes);
   if (!handle.is_valid())
     return nullptr;
 
   base::SharedMemoryHandle platform_handle;
   size_t shared_memory_size;
   bool readonly;
   MojoResult result = mojo::UnwrapSharedMemoryHandle(
       std::move(handle), &platform_handle, &shared_memory_size, &readonly);
   if (result != MOJO_RESULT_OK)
     return nullptr;
   DCHECK_EQ(shared_memory_size, bytes);
 
   auto shared_memory =
       base::MakeUnique<base::SharedMemory>(platform_handle, readonly);
   return base::WrapUnique<gfx::GpuMemoryBuffer>(
       new MojoGpuMemoryBufferImpl(size, format, std::move(shared_memory)));
 }
 
+// static
+std::unique_ptr<gfx::GpuMemoryBuffer> MojoGpuMemoryBufferImpl::CreateFromHandle(
+    const gfx::GpuMemoryBufferHandle& handle,
+    const gfx::Size& size,
+    gfx::BufferFormat format,
+    gfx::BufferUsage usage) {
+  DCHECK_EQ(handle.type, gfx::SHARED_MEMORY_BUFFER);
+  DCHECK(base::SharedMemory::IsHandleValid(handle.handle));
+  const bool readonly = false;
+  auto shared_memory =
+      base::MakeUnique<base::SharedMemory>(handle.handle, readonly);
+  return base::WrapUnique<gfx::GpuMemoryBuffer>(

[dcheng, 2016/08/17 22:59:00]

Nit: Omit the template parameter here (WrapUnique autodeduces)

[Peng, 2016/08/17 23:28:17]

Done.

+      new MojoGpuMemoryBufferImpl(size, format, std::move(shared_memory)));
+}
+
 MojoGpuMemoryBufferImpl* MojoGpuMemoryBufferImpl::FromClientBuffer(
     ClientBuffer buffer) {
   return reinterpret_cast<MojoGpuMemoryBufferImpl*>(buffer);
 }
 
 const unsigned char* MojoGpuMemoryBufferImpl::GetMemory() const {
   return static_cast<const unsigned char*>(shared_memory_->memory());
 }
 
 bool MojoGpuMemoryBufferImpl::Map() {
@@ skipping 32 matching lines @@
       gfx::RowSizeForBufferFormat(size_.width(), format_, 0));
 
   return handle;
 }
 
 gfx::GpuMemoryBufferType MojoGpuMemoryBufferImpl::GetBufferType() const {
   return gfx::SHARED_MEMORY_BUFFER;
 }
 
 }  // namespace ui