remove references to DEPRECATED SkBitmap::kA1_Config. No functional change expected.

ui/gfx/ozone/dri/dri_skbitmap.cc

 // 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.
 
 #include "ui/gfx/ozone/dri/dri_skbitmap.h"
 
 #include <errno.h>
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <xf86drm.h>
@@ skipping 171 matching lines @@
 }
 
 bool DriSkBitmap::Initialize() {
   DriAllocator drm_allocator;
   return allocPixels(&drm_allocator, NULL);
 }
 
 uint8_t DriSkBitmap::GetColorDepth() const {
   switch (config()) {
     case SkBitmap::kNo_Config:
-    case SkBitmap::kA1_Config:
     case SkBitmap::kA8_Config:
       return 0;
     case SkBitmap::kIndex8_Config:
       return 8;
     case SkBitmap::kRGB_565_Config:
       return 16;
     case SkBitmap::kARGB_4444_Config:
       return 12;
     case SkBitmap::kARGB_8888_Config:
       return 24;
     default:
       NOTREACHED();
       return 0;
   }
 }
 
 }  // namespace gfx