cocoa: draw tabstrip stroke in white in increase-contrast incognito

chrome/browser/ui/cocoa/tabs/tab_view.mm

Index: chrome/browser/ui/cocoa/tabs/tab_view.mm
diff --git a/chrome/browser/ui/cocoa/tabs/tab_view.mm b/chrome/browser/ui/cocoa/tabs/tab_view.mm
index 3804cfa6e64268254a1c1f0da9010bfc88d5640b..6263deaac59aa2e18f53e08d48567e9ddcf30c44 100644
--- a/chrome/browser/ui/cocoa/tabs/tab_view.mm
+++ b/chrome/browser/ui/cocoa/tabs/tab_view.mm
@@ -80,6 +80,10 @@ @interface TabHeavyImageMaker : TabImageMaker
 + (void)setTabEdgeStrokeColor;
 @end
 
+@interface TabHeavyInvertedImageMaker : TabImageMaker
++ (void)setTabEdgeStrokeColor;
+@end
+
 @interface TabController(Private)
 // The TabView's close button.
 - (HoverCloseButton*)closeButton;
@@ -92,8 +96,20 @@ - (HoverCloseButton*)closeButton;
 enum StrokeType {
   STROKE_NORMAL,
   STROKE_HEAVY,
+  STROKE_HEAVY_INVERTED,
 };
 
+Class drawingClassForStrokeType(StrokeType stroke_type) {
+  switch (stroke_type) {
+    case STROKE_NORMAL:
+      return [TabImageMaker class];
+    case STROKE_HEAVY:
+      return [TabHeavyImageMaker class];
+    case STROKE_HEAVY_INVERTED:
+      return [TabHeavyInvertedImageMaker class];
+  }
+}
+
 NSImage* imageForResourceID(int resource_id, StrokeType stroke_type) {
   CGFloat imageWidth = resource_id == IDR_TAB_ACTIVE_CENTER ? 1 : 18;
   SEL theSelector = 0;
@@ -120,8 +136,7 @@ - (HoverCloseButton*)closeButton;
   }
   DCHECK(theSelector);
 
-  Class makerClass = stroke_type == STROKE_HEAVY ? [TabHeavyImageMaker class]
-                                                 : [TabImageMaker class];
+  Class makerClass = drawingClassForStrokeType(stroke_type);
   base::scoped_nsobject<NSCustomImageRep> imageRep([[NSCustomImageRep alloc]
       initWithDrawSelector:theSelector
                   delegate:makerClass]);
@@ -154,8 +169,20 @@ - (HoverCloseButton*)closeButton;
       (imageForResourceID(IDR_TAB_ACTIVE_LEFT, STROKE_HEAVY),
        imageForResourceID(IDR_TAB_ACTIVE_CENTER, STROKE_HEAVY),
        imageForResourceID(IDR_TAB_ACTIVE_RIGHT, STROKE_HEAVY)));
-
-  return stroke_type == STROKE_HEAVY ? heavyStroke : stroke;
+  CR_DEFINE_STATIC_LOCAL(
+      ui::ThreePartImage, heavyInvertedStroke,
+      (imageForResourceID(IDR_TAB_ACTIVE_LEFT, STROKE_HEAVY_INVERTED),
+       imageForResourceID(IDR_TAB_ACTIVE_CENTER, STROKE_HEAVY_INVERTED),
+       imageForResourceID(IDR_TAB_ACTIVE_RIGHT, STROKE_HEAVY_INVERTED)));
+
+  switch (stroke_type) {
+    case STROKE_NORMAL:
+      return stroke;
+    case STROKE_HEAVY:
+      return heavyStroke;
+    case STROKE_HEAVY_INVERTED:
+      return heavyInvertedStroke;
+  }
 }
 
 CGFloat LineWidthFromContext(CGContextRef context) {
@@ -521,10 +548,12 @@ - (void)drawStroke:(NSRect)dirtyRect {
   clipRect.origin.y += [self cr_lineWidth];
   NSRectClip(clipRect);
   const ui::ThemeProvider* provider = [[self window] themeProvider];
-  GetStrokeImage(state_ == NSOnState,
-                 provider && provider->ShouldIncreaseContrast()
-                     ? STROKE_HEAVY
-                     : STROKE_NORMAL)
+  StrokeType stroke_type = STROKE_NORMAL;
+  if (provider && provider->ShouldIncreaseContrast()) {
+    stroke_type =
+        [[self window] hasDarkTheme] ? STROKE_HEAVY_INVERTED : STROKE_HEAVY;
+  }
+  GetStrokeImage(state_ == NSOnState, stroke_type)
       .DrawInRect(bounds, NSCompositeSourceOver, alpha);
 }
 
@@ -1032,3 +1061,17 @@ + (void)setTabEdgeStrokeColor {
 }
 
 @end
+
+@implementation TabHeavyInvertedImageMaker
+
+// For "Increase Contrast" mode, when using a dark theme, the stroke should be
+// drawn in flat white instead of flat black. There is normally no need to
+// special-case this since the lower-contrast border is equally visible in light
+// or dark themes.
++ (void)setTabEdgeStrokeColor {
+  static NSColor* heavyStrokeColor =
+      [skia::SkColorToSRGBNSColor(SK_ColorWHITE) retain];
+  [heavyStrokeColor set];
+}
+
+@end