Change most uses of Pickle to base::Pickle

ipc/mojo/ipc_mojo_bootstrap.cc

Index: ipc/mojo/ipc_mojo_bootstrap.cc
diff --git a/ipc/mojo/ipc_mojo_bootstrap.cc b/ipc/mojo/ipc_mojo_bootstrap.cc
index d307246033ffced61d2c4ba3a3b6a0dc72b67c9d..cd9b24a523e2b9eae9ed2a90cbfd8652d8daf592 100644
--- a/ipc/mojo/ipc_mojo_bootstrap.cc
+++ b/ipc/mojo/ipc_mojo_bootstrap.cc
@@ -141,7 +141,7 @@ bool MojoClientBootstrap::OnMessageReceived(const Message& message) {
   }
 
   PlatformFileForTransit pipe;
-  PickleIterator iter(message);
+  base::PickleIterator iter(message);
   if (!ParamTraits<PlatformFileForTransit>::Read(&message, &iter, &pipe)) {
     LOG(WARNING) << "Failed to read a file handle from bootstrap channel.";
     message.set_dispatch_error();