ui: Add gfx::BufferUsage::SCANOUT_CPU_READ_WRITE.

ui/ozone/platform/drm/client_native_pixmap_factory_gbm.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 "ui/ozone/platform/drm/client_native_pixmap_factory_gbm.h"
 
 #include <utility>
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
@@ skipping 39 matching lines @@
       case gfx::BufferUsage::GPU_READ:
         return format == gfx::BufferFormat::BGR_565 ||
                format == gfx::BufferFormat::RGBA_8888 ||
                format == gfx::BufferFormat::RGBX_8888 ||
                format == gfx::BufferFormat::BGRA_8888 ||
                format == gfx::BufferFormat::BGRX_8888 ||
                format == gfx::BufferFormat::YVU_420;
       case gfx::BufferUsage::SCANOUT:
         return format == gfx::BufferFormat::BGRX_8888 ||
                format == gfx::BufferFormat::RGBX_8888;
+      case gfx::BufferUsage::SCANOUT_CPU_READ_WRITE:
+        return format == gfx::BufferFormat::BGRX_8888 ||
+               format == gfx::BufferFormat::BGRA_8888 ||
+               format == gfx::BufferFormat::RGBX_8888 ||
+               format == gfx::BufferFormat::RGBA_8888;
       case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE:
       case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE_PERSISTENT: {
 #if defined(OS_CHROMEOS)
         return
 #if defined(ARCH_CPU_X86_FAMILY)
             // Currently only Intel driver (i.e. minigbm and Mesa) supports R_8
             // and RG_88. crbug.com/356871
             format == gfx::BufferFormat::R_8 ||
             format == gfx::BufferFormat::RG_88 ||
 #endif
             format == gfx::BufferFormat::BGRA_8888;
 #else
         return false;
 #endif
       }
     }
     NOTREACHED();
     return false;
   }
   std::unique_ptr<ClientNativePixmap> ImportFromHandle(
       const gfx::NativePixmapHandle& handle,
       const gfx::Size& size,
       gfx::BufferUsage usage) override {
     DCHECK(!handle.fds.empty());
     switch (usage) {
+      case gfx::BufferUsage::SCANOUT_CPU_READ_WRITE:

[dcheng, 2017/02/27 23:14:56]

Quick question: are these only supposed to be used on CrOS?

[reveman, 2017/02/27 23:47:23]

They can be used on other platforms too. The scanout ones might not make as much
sense on other platforms today but they should still work.

       case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE:
       case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE_PERSISTENT:
 #if defined(OS_CHROMEOS)
         return ClientNativePixmapDmaBuf::ImportFromDmabuf(handle, size);
 #else
         NOTREACHED();
         return nullptr;
 #endif
       case gfx::BufferUsage::GPU_READ:
       case gfx::BufferUsage::SCANOUT:
         // Close all the fds.
         for (const auto& fd : handle.fds)
           base::ScopedFD scoped_fd(fd.fd);
         return base::WrapUnique(new ClientNativePixmapGbm);
     }
     NOTREACHED();
     return nullptr;
   }
 
   DISALLOW_COPY_AND_ASSIGN(ClientNativePixmapFactoryGbm);
 };
 
 ClientNativePixmapFactory* CreateClientNativePixmapFactoryGbm() {
   return new ClientNativePixmapFactoryGbm();
 }
 
 }  // namespace ui