[Mac][Material Design] Fix regression with infobar border.

chrome/browser/ui/cocoa/infobars/infobar_gradient_view.mm

Index: chrome/browser/ui/cocoa/infobars/infobar_gradient_view.mm
diff --git a/chrome/browser/ui/cocoa/infobars/infobar_gradient_view.mm b/chrome/browser/ui/cocoa/infobars/infobar_gradient_view.mm
index 4bf8cb26542e46ac4503bf78b12d0c09f23f066e..f00e1d46082c548b4d6379a102486160a1e06e74 100644
--- a/chrome/browser/ui/cocoa/infobars/infobar_gradient_view.mm
+++ b/chrome/browser/ui/cocoa/infobars/infobar_gradient_view.mm
@@ -52,14 +52,10 @@
   if (!themeProvider)
     return [NSColor blackColor];
 
-  if (!ui::MaterialDesignController::IsModeMaterial()) {
-    BOOL active = [[self window] isMainWindow];
-    return themeProvider->GetNSColor(
-        active ? ThemeProperties::COLOR_TOOLBAR_STROKE :
-                 ThemeProperties::COLOR_TOOLBAR_STROKE_INACTIVE);
-  }
+  BOOL active = [[self window] isMainWindow];
   return themeProvider->GetNSColor(
-             ThemeProperties::COLOR_DETACHED_BOOKMARK_BAR_SEPARATOR);
+      active ? ThemeProperties::COLOR_TOOLBAR_STROKE :
+               ThemeProperties::COLOR_TOOLBAR_STROKE_INACTIVE);
 }
 
 - (void)drawRect:(NSRect)rect {