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

chrome/browser/ui/cocoa/image_button_cell.h

Index: chrome/browser/ui/cocoa/image_button_cell.h
diff --git a/chrome/browser/ui/cocoa/image_button_cell.h b/chrome/browser/ui/cocoa/image_button_cell.h
index e1535d41fe337ddf06ba207e53040258de253313..e539284c71ce34be98d8a012d0386cf5d9b10666 100644
--- a/chrome/browser/ui/cocoa/image_button_cell.h
+++ b/chrome/browser/ui/cocoa/image_button_cell.h
@@ -9,6 +9,10 @@
 
 #include "base/mac/scoped_nsobject.h"
 
+namespace ui {
+class ThemeProvider;
+}
+
 namespace image_button_cell {
 
 // Possible states
@@ -64,6 +68,10 @@ enum ButtonState {
 // Gets the alpha to use to draw the button for the current window focus state.
 - (CGFloat)imageAlphaForWindowState:(NSWindow*)window;
 
+// Returns the theme provider for the given |window|; this allows subclasses to
+// pass in a different theme provider to use if appropriate.
+- (ui::ThemeProvider*)themeProviderForWindow:(NSWindow*)window;
+
 // Draws the cell's image within |cellFrame|.
 - (void)drawImageWithFrame:(NSRect)cellFrame inView:(NSView*)controlView;