omnibox: use dark border stroke in Increase Contrast mode

chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm

Index: chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm
diff --git a/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm b/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm
index f7b55825e0ed2cc0bf6c4327197ceacec888c2cf..02ba77a04b7e081577d5b2d927b2c09fd19db029 100644
--- a/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm
+++ b/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_cell.mm
@@ -361,12 +361,22 @@ size_t CalculatePositionsInFrame(
   }
 
   // Draw the border.
+  const ui::ThemeProvider* provider = [[controlView window] themeProvider];
+  bool increaseContrast = provider && provider->ShouldIncreaseContrast();
   if (!inDarkMode) {
-    const CGFloat kNormalStrokeGray = 168 / 255.;
-    [[NSColor colorWithCalibratedWhite:kNormalStrokeGray alpha:1] set];
+    if (increaseContrast) {
+      [[NSColor blackColor] set];
+    } else {
+      const CGFloat kNormalStrokeGray = 168 / 255.;
+      [[NSColor colorWithCalibratedWhite:kNormalStrokeGray alpha:1] set];
+    }
   } else {
-    const CGFloat k30PercentAlpha = 0.3;
-    [[NSColor colorWithCalibratedWhite:0 alpha:k30PercentAlpha] set];
+    if (increaseContrast) {
+      [[NSColor whiteColor] set];
+    } else {
+      const CGFloat k30PercentAlpha = 0.3;
+      [[NSColor colorWithCalibratedWhite:0 alpha:k30PercentAlpha] set];
+    }
   }
   [path stroke];