Add compositor support for half-float RGBA buffers and textures

cc/resources/resource_format_utils.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 "cc/resources/resource_format_utils.h"
 
 namespace cc {
 
 SkColorType ResourceFormatToClosestSkColorType(ResourceFormat format) {
   // Use kN32_SkColorType if there is no corresponding SkColorType.
   switch (format) {
     case RGBA_4444:
       return kARGB_4444_SkColorType;
     case RGBA_8888:
     case BGRA_8888:
       return kN32_SkColorType;
     case ALPHA_8:
       return kAlpha_8_SkColorType;
     case RGB_565:
       return kRGB_565_SkColorType;
     case LUMINANCE_8:
       return kGray_8_SkColorType;
     case ETC1:
     case RED_8:
     case LUMINANCE_F16:
       return kN32_SkColorType;
+    case RGBA_F16:
+      return kRGBA_F16_SkColorType;
   }
   NOTREACHED();
   return kN32_SkColorType;
 }
 
 }  // namespace cc