net: Update the include paths of base/string_piece.h to its new location.

string_piece.h was moved into base/strings/ in r191206 -
https://chromiumcodereview.appspot.com/12982018/

[email protected],[email protected]

Review URL: https://codereview.chromium.org/14223008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@194055 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/net/spdy/spdy_frame_builder.h b/net/spdy/spdy_frame_builder.h
index db67b0a..7f9b3b1b 100644
--- a/net/spdy/spdy_frame_builder.h
+++ b/net/spdy/spdy_frame_builder.h
@@ -9,7 +9,7 @@
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 #include "base/sys_byteorder.h"
 #include "net/base/net_export.h"
 #include "net/spdy/spdy_protocol.h"