Adjust web notification tray height.

ash/system/web_notification/web_notification_tray.cc

Index: ash/system/web_notification/web_notification_tray.cc
diff --git a/ash/system/web_notification/web_notification_tray.cc b/ash/system/web_notification/web_notification_tray.cc
index a9e439e9dcf77d01e6e0a9556d7d2b4891835bc8..1d820b4d3422211c8af8fff11982208cc76bba83 100644
--- a/ash/system/web_notification/web_notification_tray.cc
+++ b/ash/system/web_notification/web_notification_tray.cc
@@ -43,7 +43,7 @@ const int kTrayContainerHorizontalPaddingVerticalAlignment = 0;
 const int kPaddingFromLeftEdgeOfSystemTrayBottomAlignment = 8;
 const int kPaddingFromTopEdgeOfSystemTrayVerticalAlignment = 10;
 const int kTrayWidth = 40;
-const int kTrayHeight = 32;
+const int kTrayHeight = 31;
 const int kTraySideWidth = 32;
 const int kTraySideHeight = 24;