[Extensions Toolbar Mac] Adjust button threshold for hiding

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

Index: chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm
diff --git a/chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm b/chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm
index 40a8f59563cbccea9d08c5d33ae3220d5b3379e1..040b863331524c7c67c52c6ceef55c2a0f77e150 100644
--- a/chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm
+++ b/chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm
@@ -631,10 +631,10 @@ void ToolbarActionsBarBridge::OnOverflowedActionWantsToRunChanged(
 
     CGFloat intersectionWidth =
         NSWidth(NSIntersectionRect([containerView_ bounds], buttonFrame));
-    // Pad the threshold by 5 pixels in order to have the buttons hide more
-    // easily.
+    // Hide the button if it's not "mostly" visible. "Mostly" here equates to
+    // having three or fewer pixels hidden.
     if (([containerView_ grippyPinned] && intersectionWidth > 0) ||
-        (intersectionWidth <= (NSWidth(buttonFrame) / 2) + 5.0)) {
+        (intersectionWidth <= NSWidth(buttonFrame) - 3.0)) {
       [button setAlphaValue:0.0];
       [button removeFromSuperview];
     }