Enables 300P support for iOS.

ui/gfx/image/image_ios_unittest.mm

+// Copyright (c) 2014 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.
+
+#import <QuartzCore/QuartzCore.h>
+#import <UIKit/UIKit.h>
+
+#include "base/logging.h"
+#include "base/mac/scoped_cftyperef.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/image/image.h"
+#include "ui/gfx/image/image_skia.h"
+
+namespace {
+
+// Helper function to return a UIImage with the given size and scale.
+UIImage* UIImageWithSizeAndScale(CGFloat width, CGFloat height, CGFloat scale) {
+  CGSize target_size = CGSizeMake(width * scale, height * scale);
+
+  base::ScopedCFTypeRef<CGColorSpaceRef> color_space(

[Robert Sesek, 2014/09/16 15:51:30]

Could you use CreateImage() here (in image_unittest_util.h)?

[rohitrao (ping after 24h), 2014/09/16 17:20:52]

I'm intentionally creating a UIImage from scratch here, so that I know exactly
what size UIImage I'm starting with.  All of the test utils, including
CreateImage(), create an SkBitmap first and then convert to what's asked for. 
I'll add a comment.

+      CGColorSpaceCreateDeviceRGB());
+  base::ScopedCFTypeRef<CGContextRef> context(CGBitmapContextCreate(
+      NULL,
+      target_size.width,
+      target_size.height,
+      8,
+      target_size.width * 4,
+      color_space,
+      kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host));
+
+  CGRect target_rect = CGRectMake(0, 0,
+                                  target_size.width, target_size.height);
+  CGContextSetFillColorWithColor(context, [[UIColor redColor] CGColor]);
+  CGContextFillRect(context, target_rect);
+
+  base::ScopedCFTypeRef<CGImageRef> cg_image(
+      CGBitmapContextCreateImage(context));
+  return [UIImage imageWithCGImage:cg_image
+                             scale:scale
+                       orientation:UIImageOrientationUp];
+}
+
+class ImageIOSTest : public testing::Test {

[Robert Sesek, 2014/09/16 15:51:30]

You could delete this class and just use TEST(ImageIOSTest,
ImageConversionWithUnsupportedScaleFactor).

[rohitrao (ping after 24h), 2014/09/16 17:20:52]

Done.  I'll bring the fixture back when I need it.

Do I need to save/restore the original set of SupportedScaleFactors?  I'm not
sure any other tests bother.

[Robert Sesek, 2014/09/16 17:26:16]

It might be a good idea to do that.

+ public:
+  ImageIOSTest() {}
+  virtual ~ImageIOSTest() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ImageIOSTest);
+};
+
+// Tests image conversion when the scale factor of the source image is not in
+// the list of supported scale factors.
+TEST_F(ImageIOSTest, ImageConversionWithUnsupportedScaleFactor) {
+  const CGFloat kWidth = 200;
+  const CGFloat kHeight = 100;
+  const CGFloat kTestScales[3] = { 1.0f, 2.0f, 3.0f };
+
+  for (size_t i = 0; i < arraysize(kTestScales); ++i) {
+    for (size_t j = 0; j < arraysize(kTestScales); ++j) {
+      const CGFloat source_scale = kTestScales[i];
+      const CGFloat supported_scale = kTestScales[j];
+
+      // Set the supported scale for testing.
+      std::vector<float> supported_scales;
+      supported_scales.push_back(supported_scale);
+      gfx::ImageSkia::SetSupportedScales(supported_scales);
+
+      // Create an UIImage with the appropriate source_scale.
+      UIImage* ui_image =
+          UIImageWithSizeAndScale(kWidth, kHeight, source_scale);
+      ASSERT_EQ(kWidth, ui_image.size.width);
+      ASSERT_EQ(kHeight, ui_image.size.height);
+      ASSERT_EQ(source_scale, ui_image.scale);
+
+      // Convert to SkBitmap and test its size.
+      gfx::Image to_skbitmap([ui_image retain]);
+      const SkBitmap* bitmap = to_skbitmap.ToSkBitmap();
+      ASSERT_TRUE(bitmap != NULL);
+      EXPECT_EQ(kWidth * supported_scale, bitmap->width());
+      EXPECT_EQ(kHeight * supported_scale, bitmap->height());
+
+      // Convert to ImageSkia and test its size.
+      gfx::Image to_imageskia([ui_image retain]);
+      const gfx::ImageSkia* imageskia = to_imageskia.ToImageSkia();
+      EXPECT_EQ(kWidth, imageskia->width());
+      EXPECT_EQ(kHeight, imageskia->height());
+
+      // TODO(rohitrao): Convert from ImageSkia back to UIImage.  This should
+      // scale the image based on the current set of supported scales.
+    }
+  }
+}
+
+} // namespace