Add GenericSharedMemoryId and use w/ GpuMemoryBuffer

ui/gfx/gpu_memory_buffer.h

 // Copyright 2013 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.
 
 #ifndef UI_GFX_GPU_MEMORY_BUFFER_H_
 #define UI_GFX_GPU_MEMORY_BUFFER_H_
 
+#include "base/memory/generic_shared_memory_id.h"
 #include "base/memory/shared_memory.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "build/build_config.h"
 #include "ui/gfx/buffer_types.h"
 #include "ui/gfx/gfx_export.h"
 
 extern "C" typedef struct _ClientBuffer* ClientBuffer;
 
 namespace gfx {
 
 enum GpuMemoryBufferType {
   EMPTY_BUFFER,
   SHARED_MEMORY_BUFFER,
   IO_SURFACE_BUFFER,
   SURFACE_TEXTURE_BUFFER,
   OZONE_NATIVE_PIXMAP,
   GPU_MEMORY_BUFFER_TYPE_LAST = OZONE_NATIVE_PIXMAP
 };
 
-using GpuMemoryBufferId = int32;
+using GpuMemoryBufferId = base::GenericSharedMemoryId;
 
 struct GFX_EXPORT GpuMemoryBufferHandle {
   GpuMemoryBufferHandle();
   bool is_null() const { return type == EMPTY_BUFFER; }
   GpuMemoryBufferType type;
   GpuMemoryBufferId id;
   base::SharedMemoryHandle handle;
 };
 
-base::trace_event::MemoryAllocatorDumpGuid GFX_EXPORT
-GetGpuMemoryBufferGUIDForTracing(uint64 tracing_process_id,
-                                 GpuMemoryBufferId buffer_id);

[reveman, 2015/08/10 18:57:32]

Maybe keep this for single process mode where gpu memory buffer implementations
might not be backed by some type of shared memory. e.g. PBO backed GMBs.

[ericrk, 2015/08/10 21:12:14]

Seems like using GenericSharedMemoryId for these in single process mode is the
most straightforward thing rather than special casing this, espeically as
GpuMemoryBufferId == base::GenericSharedMemoryId? Were you just suggesting just
keeping this function/name as a wrapper?

[reveman, 2015/08/10 22:16:13]

Yes, maybe just keeping the function as a wrapper for now as the implementation
might change in the future. While using GenericSharedMemoryId for GMBs not
backed by shared memory is probably fine, using a
"genericsharedmemory-x-process/%" guid might be less appropriate.

[ericrk, 2015/08/11 01:40:07]

sounds good.

-
 // This interface typically correspond to a type of shared memory that is also
 // shared with the GPU. A GPU memory buffer can be written to directly by
 // regular CPU code, but can also be read by the GPU.
 class GFX_EXPORT GpuMemoryBuffer {
  public:
   virtual ~GpuMemoryBuffer() {}
 
   // Maps each plane of the buffer into the client's address space so it can be
   // written to by the CPU. A pointer to plane K is stored at index K-1 of the
   // |data| array. This call may block, for instance if the GPU needs to finish
@@ skipping 21 matching lines @@
   // Returns a platform specific handle for this buffer.
   virtual GpuMemoryBufferHandle GetHandle() const = 0;
 
   // Type-checking downcast routine.
   virtual ClientBuffer AsClientBuffer() = 0;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_GPU_MEMORY_BUFFER_H_