Always add 100P scale format in the supported format list.

ui/gfx/image/image_skia_util_ios.mm

 // Copyright 2012 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/image/image_skia_util_ios.h"
 
 #include <UIKit/UIKit.h>
 
 #include "base/logging.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "skia/ext/skia_utils_ios.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/image/image_skia.h"
 
 namespace gfx {
 
 gfx::ImageSkia ImageSkiaFromUIImage(UIImage* image) {
   gfx::ImageSkia image_skia;
   if (!image)
     return image_skia;
 
-  // iOS only supports one scale factor.
-  std::vector<ui::ScaleFactor> supported_scale_factors =
-      ui::GetSupportedScaleFactors();
-  DCHECK_EQ(1U, supported_scale_factors.size());
-  if (supported_scale_factors.size() < 1)
-    return image_skia;
-
-  ui::ScaleFactor scale_factor = supported_scale_factors[0];
+  ui::ScaleFactor scale_factor = ui::GetMaxScaleFactor();
   float scale = ui::GetScaleFactorScale(scale_factor);
   CGSize size = image.size;
   CGSize desired_size_for_scale =
       CGSizeMake(size.width * scale, size.height * scale);
   SkBitmap bitmap(gfx::UIImageToSkBitmap(image, desired_size_for_scale, false));
   if (!bitmap.isNull())
     image_skia.AddRepresentation(gfx::ImageSkiaRep(bitmap, scale_factor));
   return image_skia;
 }
 
 UIImage* UIImageFromImageSkia(const gfx::ImageSkia& image_skia) {
   if (image_skia.isNull())
     return nil;
 
-  // iOS only supports one scale factor.
-  std::vector<ui::ScaleFactor> supported_scale_factors =
-      ui::GetSupportedScaleFactors();
-  DCHECK_EQ(1U, supported_scale_factors.size());
-  if (supported_scale_factors.size() < 1)
-    return nil;
-
-  ui::ScaleFactor scale_factor = supported_scale_factors[0];
+  ui::ScaleFactor scale_factor = ui::GetMaxScaleFactor();
   float scale = ui::GetScaleFactorScale(scale_factor);
   image_skia.EnsureRepsForSupportedScaleFactors();
-  const ImageSkiaRep& rep =
-      image_skia.GetRepresentation(supported_scale_factors[0]);
+  const ImageSkiaRep& rep = image_skia.GetRepresentation(scale_factor);
   base::mac::ScopedCFTypeRef<CGColorSpaceRef> color_space(
       CGColorSpaceCreateDeviceRGB());
   return gfx::SkBitmapToUIImageWithColorSpace(rep.sk_bitmap(), scale,
                                               color_space);
 }
 
 }  // namespace gfx