[Extensions Toolbar Mac] Allow the overflow toolbar to use the theme provider

chrome/browser/ui/cocoa/extensions/browser_action_button.mm

Index: chrome/browser/ui/cocoa/extensions/browser_action_button.mm
diff --git a/chrome/browser/ui/cocoa/extensions/browser_action_button.mm b/chrome/browser/ui/cocoa/extensions/browser_action_button.mm
index 74fdd8acedec024992176b5df43ceef7919f718e..a4b7ba874c3c90f777796160acd71b92b7485d94 100644
--- a/chrome/browser/ui/cocoa/extensions/browser_action_button.mm
+++ b/chrome/browser/ui/cocoa/extensions/browser_action_button.mm
@@ -11,8 +11,10 @@
 #include "base/strings/sys_string_conversions.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_window.h"
 #import "chrome/browser/ui/cocoa/extensions/browser_actions_controller.h"
 #import "chrome/browser/ui/cocoa/extensions/extension_action_context_menu_controller.h"
+#import "chrome/browser/ui/cocoa/themed_window.h"
 #import "chrome/browser/ui/cocoa/toolbar/toolbar_action_view_delegate_cocoa.h"
 #include "chrome/browser/ui/toolbar/toolbar_action_view_controller.h"
 #include "grit/theme_resources.h"
@@ -401,4 +403,13 @@ void ToolbarActionViewDelegateBridge::SetContextMenuController(
               forWebContents:webContents];
 }
 
+- (ui::ThemeProvider*)themeProviderForWindow:(NSWindow*)window {
+  ui::ThemeProvider* themeProvider = [window themeProvider];
+  if (!themeProvider)
+    themeProvider =
+        [[browserActionsController_ browser]->window()->GetNativeWindow()
+            themeProvider];
+  return themeProvider;
+}
+
 @end