Mojo: Add DCHECKs to entrypoints that CoreImpl has been initialized.

mojo/system/core.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/public/system/core.h"
 
+#include "base/logging.h"
 #include "mojo/system/core_impl.h"
 
 extern "C" {
 
 MojoResult MojoClose(MojoHandle handle) {
+  DCHECK(mojo::system::CoreImpl::Get()) << "CoreImpl not initialized.";
   return mojo::system::CoreImpl::Get()->Close(handle);
 }
 
 MojoResult MojoWait(MojoHandle handle,
                     MojoWaitFlags flags,
                     MojoDeadline deadline) {
+  DCHECK(mojo::system::CoreImpl::Get()) << "CoreImpl not initialized.";
   return mojo::system::CoreImpl::Get()->Wait(handle, flags, deadline);
 }
 
 MojoResult MojoWaitMany(const MojoHandle* handles,
                         const MojoWaitFlags* flags,
                         uint32_t num_handles,
                         MojoDeadline deadline) {
+  DCHECK(mojo::system::CoreImpl::Get()) << "CoreImpl not initialized.";
   return mojo::system::CoreImpl::Get()->WaitMany(handles, flags, num_handles,
                                                  deadline);
 }
 
 MojoResult MojoCreateMessagePipe(MojoHandle* handle_0, MojoHandle* handle_1) {
+  DCHECK(mojo::system::CoreImpl::Get()) << "CoreImpl not initialized.";
   return mojo::system::CoreImpl::Get()->CreateMessagePipe(handle_0, handle_1);
 }
 
 MojoResult MojoWriteMessage(MojoHandle handle,
                             const void* bytes, uint32_t num_bytes,
                             const MojoHandle* handles, uint32_t num_handles,
                             MojoWriteMessageFlags flags) {
+  DCHECK(mojo::system::CoreImpl::Get()) << "CoreImpl not initialized.";
   return mojo::system::CoreImpl::Get()->WriteMessage(handle,
                                                      bytes, num_bytes,
                                                      handles, num_handles,
                                                      flags);
 }
 
 MojoResult MojoReadMessage(MojoHandle handle,
                            void* bytes, uint32_t* num_bytes,
                            MojoHandle* handles, uint32_t* num_handles,
                            MojoReadMessageFlags flags) {
+  DCHECK(mojo::system::CoreImpl::Get()) << "CoreImpl not initialized.";
   return mojo::system::CoreImpl::Get()->ReadMessage(handle,
                                                     bytes, num_bytes,
                                                     handles, num_handles,
                                                     flags);
 }
 
 }  // extern "C"