`#pragma once` for app, base, chrome, gfx, ipc, net, skia, views

BUG=50273
TEST=everything still builds, build is 10% faster on windows, same speed on mac/linux

TBR: erg

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@53716 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: 32b76eff6f630b9bcc0fc3f3bad826f3d1217dda
diff --git a/base/tuple.h b/base/tuple.h
index d17d9f5..bcd2ad4 100644
--- a/base/tuple.h
+++ b/base/tuple.h
@@ -28,6 +28,7 @@
 
 #ifndef BASE_TUPLE_H__
 #define BASE_TUPLE_H__
+#pragma once
 
 // Traits ----------------------------------------------------------------------
 //