Fix LUMANINCE_ALPHA issue

gpu/command_buffer/common/gles2_cmd_utils.cc

 // Copyright (c) 2009 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.
 
 // This file is here so other GLES2 related files can have a common set of
 // includes where appropriate.
 
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
 #include <GLES2/gles2_command_buffer.h>
@@ skipping 305 matching lines @@
     case GL_UNSIGNED_INT_24_8_OES:
        return 1;
     default:
        break;
     }
 
     switch (format) {
     case GL_RGB:
        return 3;
     case GL_LUMINANCE_ALPHA:
+       return 2;
     case GL_RGBA:
     case GL_BGRA_EXT:
        return 4;
     case GL_ALPHA:
     case GL_LUMINANCE:
     case GL_DEPTH_COMPONENT:
     case GL_DEPTH_STENCIL_OES:
        return 1;
     default:
        return 0;
@@ skipping 185 matching lines @@
     case GL_RGB5_A1:
       return 0x000F;
     default:
       return 0x0000;
   }
 }
 
 }  // namespace gles2
 }  // namespace gpu