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

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

Index: chrome/browser/ui/cocoa/tabs/tab_strip_view.mm
diff --git a/chrome/browser/ui/cocoa/tabs/tab_strip_view.mm b/chrome/browser/ui/cocoa/tabs/tab_strip_view.mm
index a59f02047d4c99a1d3a8210c2b2066c704e47433..b3dcc322a00a3129906cc6c6515fff60906de881 100644
--- a/chrome/browser/ui/cocoa/tabs/tab_strip_view.mm
+++ b/chrome/browser/ui/cocoa/tabs/tab_strip_view.mm
@@ -85,6 +85,12 @@ - (void)drawBottomEdge:(NSRect)dirtyRect {
   } else {
     strokeColor =
         themeProvider->GetNSColor(ThemeProperties::COLOR_TOOLBAR_STROKE);
+
+    // If the current theme is the system theme, and the system is in "increase
+    // contrast" mode, and this is an incognito window, force the toolbar stroke
+    // to be drawn in white instead of black, to make it show up better.
+    if ([[self window] hasDarkTheme] && themeProvider->ShouldIncreaseContrast())
+      strokeColor = [NSColor whiteColor];
   }
 
   if (themeProvider->ShouldIncreaseContrast())