Tracing for NSMenu timelines

ui/base/cocoa/menu_controller.mm

Index: ui/base/cocoa/menu_controller.mm
diff --git a/ui/base/cocoa/menu_controller.mm b/ui/base/cocoa/menu_controller.mm
index 0c42fe7ba34504e04d011ebb24215a1f75ea9e2d..7ae478a92880aea9eb5948dfc590865bc769fc37 100644
--- a/ui/base/cocoa/menu_controller.mm
+++ b/ui/base/cocoa/menu_controller.mm
@@ -25,6 +25,9 @@ NSString* const kMenuControllerMenuDidCloseNotification =
                    atIndex:(int)index;
 @end
 
+@interface ResponsiveNSMenuItem : NSMenuItem
+@end
+
 @implementation MenuController
 
 @synthesize model = model_;
@@ -60,6 +63,8 @@ NSString* const kMenuControllerMenuDidCloseNotification =
   [self cancel];
 
   model_ = NULL;
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+
   [super dealloc];
 }
 
@@ -112,10 +117,10 @@ NSString* const kMenuControllerMenuDidCloseNotification =
     label16 = [MenuController elideMenuTitle:label16 toWidth:maxWidth];
 
   NSString* label = l10n_util::FixUpWindowsStyleLabel(label16);
-  base::scoped_nsobject<NSMenuItem> item(
-      [[NSMenuItem alloc] initWithTitle:label
-                                 action:@selector(itemSelected:)
-                          keyEquivalent:@""]);
+  base::scoped_nsobject<NSMenuItem> item([[ResponsiveNSMenuItem alloc]
+      initWithTitle:label
+             action:@selector(itemSelected:)
+      keyEquivalent:@""]);
 
   // If the menu item has an icon, set it.
   gfx::Image icon;
@@ -200,9 +205,19 @@ NSString* const kMenuControllerMenuDidCloseNotification =
   return NO;
 }
 
-// Called when the user chooses a particular menu item. |sender| is the menu
-// item chosen.
+- (void)itemWillBeSelected:(id)sender {
+  suppressNextItemSelected_ = [self processItemSelectedEarly:sender];
+}
+
+- (BOOL)processItemSelectedEarly:(id)sender {
+  return NO;
+}
+
 - (void)itemSelected:(id)sender {
+  DLOG(INFO) << "got action";
+  if (suppressNextItemSelected_)
+    return;
+
   NSInteger modelIndex = [sender tag];
   ui::MenuModel* model =
       static_cast<ui::MenuModel*>(
@@ -237,13 +252,20 @@ NSString* const kMenuControllerMenuDidCloseNotification =
 
 - (void)menuWillOpen:(NSMenu*)menu {
   isMenuOpen_ = YES;
+  suppressNextItemSelected_ = NO;
   model_->MenuWillShow();
   [[NSNotificationCenter defaultCenter]
       postNotificationName:kMenuControllerMenuWillOpenNotification
                     object:self];
+  [[NSNotificationCenter defaultCenter]
+      addObserver:self
+         selector:@selector(willSendAction:)
+             name:NSMenuWillSendActionNotification
+           object:nil];
 }
 
 - (void)menuDidClose:(NSMenu*)menu {
+  DLOG(INFO) << "did close";
   if (isMenuOpen_) {
     model_->MenuWillClose();
     isMenuOpen_ = NO;
@@ -253,4 +275,24 @@ NSString* const kMenuControllerMenuDidCloseNotification =
                     object:self];
 }
 
+- (void)willSendAction:(NSNotification*)note {
+  DLOG(INFO) << "will send action";
+}
+
+@end
+
+@interface NSMenuItem (Private)
+// Private method which is invoked very soon after the event that activates a
+// menu item is received. AppKit then spends 300ms or so flashing the menu item,
+// and fading out the menu, blocking the UI thread the entire time.
+- (void)_sendItemSelectedNote;
+@end
+
+@implementation ResponsiveNSMenuItem
+- (void)_sendItemSelectedNote {
+  DLOG(INFO) << "early";
+  if ([[self target] respondsToSelector:@selector(itemWillBeSelected:)])
+    [[self target] itemWillBeSelected:self];
+  [super _sendItemSelectedNote];
+}
 @end