The extension icon on the far right is invisible when about to dragging.

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 4163045b751496707c25d7124ec8071214c72056..67b28fb77a8dbe8378c6a5e372590bbce56d37d0 100644
--- a/chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm
+++ b/chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm
@@ -637,7 +637,9 @@ class ExtensionServiceObserverBridge
 - (void)containerDragStart:(NSNotification*)notification {
   [self setChevronHidden:YES inFrame:[containerView_ frame] animate:YES];
   while([hiddenButtons_ count] > 0) {
-    [containerView_ addSubview:[hiddenButtons_ objectAtIndex:0]];
+    BrowserActionButton* button = [hiddenButtons_ objectAtIndex:0];
+    [button setAlphaValue:1.0];
+    [containerView_ addSubview:button];
     [hiddenButtons_ removeObjectAtIndex:0];
   }
 }