cocoa: Do not show up a tooltip when hovering on the magnifying glass on NTP.

chrome/browser/ui/cocoa/location_bar/location_icon_decoration.mm

Index: chrome/browser/ui/cocoa/location_bar/location_icon_decoration.mm
diff --git a/chrome/browser/ui/cocoa/location_bar/location_icon_decoration.mm b/chrome/browser/ui/cocoa/location_bar/location_icon_decoration.mm
index efe812867463e6938e672459ddfcdec1c2372f3f..c7892a8a1bed859aee38dfde8ee8ada4ee6dffd3 100644
--- a/chrome/browser/ui/cocoa/location_bar/location_icon_decoration.mm
+++ b/chrome/browser/ui/cocoa/location_bar/location_icon_decoration.mm
@@ -19,8 +19,6 @@ const CGFloat kBubblePointYOffset = 2.0;
 
 LocationIconDecoration::LocationIconDecoration(LocationBarViewMac* owner)
     : owner_(owner) {
-  tooltip_.reset(
-      [l10n_util::GetNSStringWithFixup(IDS_TOOLTIP_LOCATION_ICON) retain]);
 }
 
 LocationIconDecoration::~LocationIconDecoration() {
@@ -77,5 +75,8 @@ bool LocationIconDecoration::OnMousePressed(NSRect frame) {
 }
 
 NSString* LocationIconDecoration::GetToolTip() {
-  return tooltip_.get();
+  if (owner_->location_entry()->IsEditingOrEmpty())
+    return nil;
+  else
+    return l10n_util::GetNSStringWithFixup(IDS_TOOLTIP_LOCATION_ICON);
 }