Don't attempt to forward declare StringPiece.

1) This is discouraged because it prevents callers from benefiting from automatic coersion from string/char* types.
2) A follow-up CL (http://codereview.chromium.org/8659047/) will make StringPiece a template, and thus awkward to forward declare. The very small number of places that were appropriately forward declaring it do not justify writing a 'string_piece_forward.h'.

BUG=87634
R=willchan@chromium.org


Review URL: http://codereview.chromium.org/8817019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113404 0039d316-1c4b-4281-b951-d872f2087c98

net/base/x509_cert_types.h

@@ -12,6 +12,7 @@
 #include <string>
 #include <vector>
 
+#include "base/string_piece.h"
 #include "build/build_config.h"
 #include "net/base/net_export.h"
 
@@ -21,7 +22,6 @@
 
 namespace base {
 class Time;
-class StringPiece;
 }  // namespace base
 
 namespace net {

net/base/x509_certificate.h

@@ -38,7 +38,6 @@ struct CERTCertificateStr;
 class Pickle;
 
 namespace crypto {
-class StringPiece;
 class RSAPrivateKey;
 }  // namespace crypto
 

net/socket/ssl_socket.h

@@ -6,12 +6,9 @@
 #define NET_SOCKET_SSL_SOCKET_H_
 
 #include "base/basictypes.h"
+#include "base/string_piece.h"
 #include "net/socket/stream_socket.h"
 
-namespace base {
-class StringPiece;
-}  // namespace base
-
 namespace net {
 
 // SSLSocket interface defines method that are common between client