Make panels turn on or off shadow effect.

chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm

Index: chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm
diff --git a/chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm b/chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm
index dd7ec1e4b0c60e311dfe47709276ff0c1f836b6b..6a054edc9a86c9c4bf5b7d48cb13cad94687efdb 100644
--- a/chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm
+++ b/chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm
@@ -923,6 +923,12 @@ NSCursor* LoadWebKitCursor(WebKit::WebCursorInfo::Type type) {
   [[self window] invalidateCursorRectsForView:overlayView_];
 }
 
+- (void)showShadow:(BOOL)show {
+  if (![self isWindowLoaded])
+    return;
+  [[self window] setHasShadow:show];
+}
+
 // We have custom implementation of these because our titlebar height is custom
 // and does not match the standard one.
 - (NSRect)frameRectForContentRect:(NSRect)contentRect {