Move NumberOfPlanesForGpuMemoryBufferFormat to gfx

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/shared_memory.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "build/build_config.h"
@@ skipping 27 matching lines @@
 GetGpuMemoryBufferGUIDForTracing(uint64 tracing_process_id,
                                  GpuMemoryBufferId buffer_id);
 
 // 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() {}
 
+  // Returns the number of planes based on the format of the buffer.
+  static size_t NumberOfPlanes(BufferFormat format);

[reveman, 2015/08/10 23:08:28]

How about we add a gpu_memory_buffer_util.h file for this type of stuff?

The reason I prefer that is that it makes it more clear that it's just an
utility function and not something that has to be used. The format definition
itself includes all the information needed and these type of utility functions
are really just needed to write type generic code in a clean way. Most usage of
the gfx::GpuMemoryBuffer interface doesn't need it.

[Andre, 2015/08/11 03:50:03]

Done.

+
   // 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
   // accessing the buffer or if CPU caches need to be synchronized. Returns
   // false on failure.
   virtual bool Map(void** data) = 0;
 
   // Unmaps the buffer. It's illegal to use the pointer returned by Map() after
   // this has been called.
   virtual void Unmap() = 0;
@@ skipping 14 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_