Add a missing animation context to bookmark bar controller.

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm

Index: chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
diff --git a/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm b/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
index c680f1987efb817cc4a944a4e3cb358f056b23a8..0c8f5a65816c732859b081e188aed7ae34e36a0e 100644
--- a/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
+++ b/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
@@ -129,6 +129,7 @@ namespace {
 
 // Duration of the bookmark bar animations.
 const NSTimeInterval kBookmarkBarAnimationDuration = 0.12;
+const NSTimeInterval kDragAndDropAnimationDuration = 0.25;
 
 void RecordAppLaunch(Profile* profile, GURL url) {
   DCHECK(profile->GetExtensionService());
@@ -1946,6 +1947,9 @@ static BOOL ValueInRangeInclusive(CGFloat low, CGFloat value, CGFloat high) {
     }
     // Put all the buttons where they belong, with all buttons to the right
     // of the insertion point shuffling right to make space for it.
+    [NSAnimationContext beginGrouping];
+    [[NSAnimationContext currentContext]
+        setDuration:kDragAndDropAnimationDuration];
     for (NSButton* button in buttons_.get()) {
       // Hidden buttons get no space.
       if ([button isHidden])
@@ -1962,6 +1966,7 @@ static BOOL ValueInRangeInclusive(CGFloat low, CGFloat value, CGFloat high) {
       else
         [button setFrame:buttonFrame];
     }
+    [NSAnimationContext endGrouping];
   }
 }