Add function to create image with size, color and scale.

Some tests needs to create an image with a given scale, so add
a function with a scale parameter.

Bug: 795669
Change-Id: Ibdc6863a247c2035cbbd5fed64c5b0954cbb2327
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Reviewed-on: https://chromium-review.googlesource.com/831514Reviewed-by: Elodie Banel <lod@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524671}

ui/base/test/ios/ui_image_test_utils.h

@@ -11,9 +11,17 @@ namespace ui {
 namespace test {
 namespace uiimage_utils {
 
-// Returns a new UIImage of size |size| with a solid color of |color|.
+// Returns a new UIImage of size |size| with a solid color of |color|. This
+// is the same as calling UIImageWithSizeAndSolidColorAndScale with a scale
+// of 1.0.
 UIImage* UIImageWithSizeAndSolidColor(CGSize const& size, UIColor* color);
 
+// Returns a new UIImage of size |size| with a solid color of |color|
+// at scale |scale|.
+UIImage* UIImageWithSizeAndSolidColorAndScale(CGSize const& size,
+                                              UIColor* color,
+                                              CGFloat scale);
+
 // Disclaimer, this is a testing function with plenty of limitations:
 // Requires the UIImages to be backed by a CGImage, ignores colorspace, may
 // return false negatives, not efficient, and probably other things.

ui/base/test/ios/ui_image_test_utils.mm

@@ -11,7 +11,13 @@ namespace test {
 namespace uiimage_utils {
 
 UIImage* UIImageWithSizeAndSolidColor(CGSize const& size, UIColor* color) {
-  UIGraphicsBeginImageContext(size);
+  return UIImageWithSizeAndSolidColorAndScale(size, color, /*scale=*/1.0);
+}
+
+UIImage* UIImageWithSizeAndSolidColorAndScale(CGSize const& size,
+                                              UIColor* color,
+                                              CGFloat scale) {
+  UIGraphicsBeginImageContextWithOptions(size, /*opaque=*/YES, scale);
   CGContextRef context = UIGraphicsGetCurrentContext();
   CGContextSetFillColorWithColor(context, [color CGColor]);
   CGContextFillRect(context, CGRectMake(0, 0, size.width, size.height));