Move NumberOfPlanesForGpuMemoryBufferFormat to gfx

ui/gfx/gpu_memory_buffer.h

Index: ui/gfx/gpu_memory_buffer.h
diff --git a/ui/gfx/gpu_memory_buffer.h b/ui/gfx/gpu_memory_buffer.h
index 263a0ef41da40ddd140556c2ccc0d73d51a30afe..f35279f474d07d5b175504c371a807cb4005bfc1 100644
--- a/ui/gfx/gpu_memory_buffer.h
+++ b/ui/gfx/gpu_memory_buffer.h
@@ -45,6 +45,9 @@ 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