Add icon to the panel titlebar on Mac.

chrome/browser/ui/panels/panel_titlebar_view_cocoa.h

Index: chrome/browser/ui/panels/panel_titlebar_view_cocoa.h
diff --git a/chrome/browser/ui/panels/panel_titlebar_view_cocoa.h b/chrome/browser/ui/panels/panel_titlebar_view_cocoa.h
index b8b478b599d2b2c9fe8804c1d72c4ccc6aedc469..eee339bac251646d5088cfb22ae958f825121314 100644
--- a/chrome/browser/ui/panels/panel_titlebar_view_cocoa.h
+++ b/chrome/browser/ui/panels/panel_titlebar_view_cocoa.h
@@ -35,6 +35,7 @@ enum PanelDragState {
 @interface PanelTitlebarViewCocoa : NSView {
  @private
   IBOutlet PanelWindowControllerCocoa* controller_;
+  IBOutlet NSImageView* icon_;
   IBOutlet NSTextField* title_;
   IBOutlet HoverImageButton* settingsButton_;
   NSButton* closeButton_;  // Created explicitly, not from NIB. Weak, destroyed
@@ -53,9 +54,11 @@ enum PanelDragState {
 - (void)attach;
 
 - (void)setTitle:(NSString*)newTitle;
+- (void)setIcon:(NSImage*)newIcon;
 
   // Should be called when size of the titlebar changes.
 - (void)updateCloseButtonLayout;
+- (void)updateIconAndTitleLayout;
 
 // We need to update our look when the Chrome theme changes or window focus
 // changes.