Mac: Fix for janky tab dragging/reordering.

chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm

Index: chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm
diff --git a/chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm b/chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm
index 06492d8374826a4705c62604ac393e8eaa595896..c08665e03d558cce4f8dd62861cf12adbb1134d6 100644
--- a/chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm
+++ b/chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm
@@ -1867,6 +1867,12 @@ NSImage* Overlay(NSImage* ground, NSImage* overlay, CGFloat alpha) {
 }
 
 - (void)mouseMoved:(NSEvent*)event {
+  // We don't want the draggged tab to repeatedly redraw its glow unnecessarily.
+  // We also want the dragged tab to keep the glow even when it slides behind
+  // another tab.
+  if ([dragController_ draggedTab])
+    return;
+
   // Use hit test to figure out what view we are hovering over.
   NSView* targetView = [tabStripView_ hitTest:[event locationInWindow]];