WebGL: Tidy up buffer allocation logic

gpu/command_buffer/common/gpu_memory_buffer_support.cc

 // Copyright 2016 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 "gpu/command_buffer/common/gpu_memory_buffer_support.h"
 
 #include <GLES2/gl2.h>
 #include <GLES2/gl2extchromium.h>
 
 #include "base/logging.h"
@@ skipping 32 matching lines @@
     case GL_RGB_YCBCR_422_CHROMIUM:
       return gfx::BufferFormat::UYVY_422;
     default:
       NOTREACHED();
       return gfx::BufferFormat::RGBA_8888;
   }
 }
 
 }  // namespace
 
-gfx::BufferFormat DefaultBufferFormatForImageFormat(unsigned internalformat) {
-  switch (internalformat) {
-    case GL_RGB:
-      return gfx::BufferFormat::BGRX_8888;
-    case GL_RGBA:
-      return gfx::BufferFormat::RGBA_8888;
-    default:
-      NOTREACHED();
-      return gfx::BufferFormat::RGBA_8888;
-  }
-}
-
 bool IsImageFormatCompatibleWithGpuMemoryBufferFormat(
     unsigned internalformat,
     gfx::BufferFormat format) {
   switch (format) {
     case gfx::BufferFormat::ATC:
     case gfx::BufferFormat::ATCIA:
     case gfx::BufferFormat::BGRA_8888:
     case gfx::BufferFormat::BGRX_8888:
     case gfx::BufferFormat::DXT1:
     case gfx::BufferFormat::DXT5:
@@ skipping 87 matching lines @@
       return size.width() % 2 == 0 && size.height() % 2 == 0;
     case gfx::BufferFormat::UYVY_422:
       return size.width() % 2 == 0;
   }
 
   NOTREACHED();
   return false;
 }
 
 }  // namespace gpu