zero-copy: Clarify to allocate/destroy GpuMemoryBuffer on any thread and use it on the main thread o

content/common/gpu/gpu_memory_buffer_factory_io_surface.cc

 // Copyright 2014 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 "content/common/gpu/gpu_memory_buffer_factory_io_surface.h"
 
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "base/logging.h"
 #include "ui/gl/gl_image_io_surface.h"
@@ skipping 86 matching lines @@
 }
 
 gfx::GpuMemoryBufferHandle
 GpuMemoryBufferFactoryIOSurface::CreateGpuMemoryBuffer(
     gfx::GpuMemoryBufferId id,
     const gfx::Size& size,
     gfx::GpuMemoryBuffer::Format format,
     gfx::GpuMemoryBuffer::Usage usage,
     int client_id,
     gfx::PluginWindowHandle surface_handle) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   base::ScopedCFTypeRef<CFMutableDictionaryRef> properties;
   properties.reset(CFDictionaryCreateMutable(kCFAllocatorDefault,
                                              0,
                                              &kCFTypeDictionaryKeyCallBacks,
                                              &kCFTypeDictionaryValueCallBacks));
   AddIntegerValue(properties, kIOSurfaceWidth, size.width());
   AddIntegerValue(properties, kIOSurfaceHeight, size.height());
   AddIntegerValue(properties, kIOSurfaceBytesPerElement, BytesPerPixel(format));
   AddIntegerValue(properties, kIOSurfacePixelFormat, PixelFormat(format));
   // TODO(reveman): Remove this when using a mach_port_t to transfer
   // IOSurface to browser and renderer process. crbug.com/323304
   AddBooleanValue(properties, kIOSurfaceIsGlobal, true);
 
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface(IOSurfaceCreate(properties));
   if (!io_surface)
     return gfx::GpuMemoryBufferHandle();
 
-  {
-    base::AutoLock lock(io_surfaces_lock_);
-
-    IOSurfaceMapKey key(id, client_id);
-    DCHECK(io_surfaces_.find(key) == io_surfaces_.end());
-    io_surfaces_[key] = io_surface;
-  }
+  IOSurfaceMapKey key(id, client_id);
+  DCHECK(io_surfaces_.find(key) == io_surfaces_.end());
+  io_surfaces_[key] = io_surface;
 
   gfx::GpuMemoryBufferHandle handle;
   handle.type = gfx::IO_SURFACE_BUFFER;
   handle.id = id;
   handle.io_surface_id = IOSurfaceGetID(io_surface);
   return handle;
 }
 
 void GpuMemoryBufferFactoryIOSurface::DestroyGpuMemoryBuffer(
     gfx::GpuMemoryBufferId id,
     int client_id) {
-  base::AutoLock lock(io_surfaces_lock_);
-
+  DCHECK(thread_checker_.CalledOnValidThread());
   IOSurfaceMapKey key(id, client_id);
   IOSurfaceMap::iterator it = io_surfaces_.find(key);
   if (it != io_surfaces_.end())
     io_surfaces_.erase(it);
 }
 
 gpu::ImageFactory* GpuMemoryBufferFactoryIOSurface::AsImageFactory() {
   return this;
 }
 
 scoped_refptr<gfx::GLImage>
 GpuMemoryBufferFactoryIOSurface::CreateImageForGpuMemoryBuffer(
     const gfx::GpuMemoryBufferHandle& handle,
     const gfx::Size& size,
     gfx::GpuMemoryBuffer::Format format,
     unsigned internalformat,
     int client_id) {
-  base::AutoLock lock(io_surfaces_lock_);
-
+  DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_EQ(handle.type, gfx::IO_SURFACE_BUFFER);
   IOSurfaceMapKey key(handle.id, client_id);
   IOSurfaceMap::iterator it = io_surfaces_.find(key);
   if (it == io_surfaces_.end())
     return scoped_refptr<gfx::GLImage>();
 
   scoped_refptr<gfx::GLImageIOSurface> image(new gfx::GLImageIOSurface(size));
   if (!image->Initialize(it->second.get()))
     return scoped_refptr<gfx::GLImage>();
 
   return image;
 }
 
 }  // namespace content