Convert NaClIPCAdapter::RewrittenMessage ownership management from shared to unique

components/nacl/loader/nacl_ipc_adapter.cc

Index: components/nacl/loader/nacl_ipc_adapter.cc
diff --git a/components/nacl/loader/nacl_ipc_adapter.cc b/components/nacl/loader/nacl_ipc_adapter.cc
index 3b1110251d1905d6fa2b9aa914dda0a3921d380c..dc521ba8f1ea1de923bffc462dbf90c084273430 100644
--- a/components/nacl/loader/nacl_ipc_adapter.cc
+++ b/components/nacl/loader/nacl_ipc_adapter.cc
@@ -250,10 +250,10 @@ std::unique_ptr<NaClDescWrapper> MakeShmNaClDesc(
 
 }  // namespace
 
-class NaClIPCAdapter::RewrittenMessage
-    : public base::RefCounted<RewrittenMessage> {
+class NaClIPCAdapter::RewrittenMessage {
  public:
   RewrittenMessage();
+  ~RewrittenMessage() {}
 
   bool is_consumed() const { return data_read_cursor_ == data_len_; }
 
@@ -267,9 +267,6 @@ class NaClIPCAdapter::RewrittenMessage
   size_t desc_count() const { return descs_.size(); }
 
  private:
-  friend class base::RefCounted<RewrittenMessage>;
-  ~RewrittenMessage() {}
-
   std::unique_ptr<char[]> data_;
   size_t data_len_;
 
@@ -539,7 +536,7 @@ bool NaClIPCAdapter::OnMessageReceived(const IPC::Message& msg) {
 bool NaClIPCAdapter::RewriteMessage(const IPC::Message& msg, uint32_t type) {
   {
     base::AutoLock lock(lock_);
-    scoped_refptr<RewrittenMessage> rewritten_msg(new RewrittenMessage);
+    std::unique_ptr<RewrittenMessage> rewritten_msg(new RewrittenMessage);
 
     typedef std::vector<ppapi::proxy::SerializedHandle> Handles;
     Handles handles;
@@ -601,9 +598,9 @@ bool NaClIPCAdapter::RewriteMessage(const IPC::Message& msg, uint32_t type) {
         rewritten_msg->AddDescriptor(nacl_desc.release());
     }
     if (new_msg)
-      SaveMessage(*new_msg, rewritten_msg.get());
+      SaveMessage(*new_msg, std::move(rewritten_msg));
     else
-      SaveMessage(msg, rewritten_msg.get());
+      SaveMessage(msg, std::move(rewritten_msg));
     cond_var_.Signal();
   }
   return true;
@@ -668,11 +665,11 @@ void NaClIPCAdapter::SaveOpenResourceMessage(
 #endif
             NACL_ABI_O_RDONLY)));
 
-    scoped_refptr<RewrittenMessage> rewritten_msg(new RewrittenMessage);
+    std::unique_ptr<RewrittenMessage> rewritten_msg(new RewrittenMessage);
     rewritten_msg->AddDescriptor(desc_wrapper.release());
     {
       base::AutoLock lock(lock_);
-      SaveMessage(*new_msg, rewritten_msg.get());
+      SaveMessage(*new_msg, std::move(rewritten_msg));
       cond_var_.Signal();
     }
     return;
@@ -686,14 +683,14 @@ void NaClIPCAdapter::SaveOpenResourceMessage(
   ppapi::proxy::SerializedHandle sh;
   sh.set_file_handle(ipc_fd, PP_FILEOPENFLAG_READ, 0);
   std::unique_ptr<IPC::Message> new_msg = CreateOpenResourceReply(orig_msg, sh);
-  scoped_refptr<RewrittenMessage> rewritten_msg(new RewrittenMessage);
+  std::unique_ptr<RewrittenMessage> rewritten_msg(new RewrittenMessage);
 
   struct NaClDesc* desc =
       NaClDescCreateWithFilePathMetadata(handle, file_path_str.c_str());
   rewritten_msg->AddDescriptor(new NaClDescWrapper(desc));
   {
     base::AutoLock lock(lock_);
-    SaveMessage(*new_msg, rewritten_msg.get());
+    SaveMessage(*new_msg, std::move(rewritten_msg));
     cond_var_.Signal();
   }
 }
@@ -715,13 +712,12 @@ int NaClIPCAdapter::LockedReceive(NaClImcTypedMsgHdr* msg) {
 
   if (locked_data_.to_be_received_.empty())
     return 0;
-  scoped_refptr<RewrittenMessage> current =
-      locked_data_.to_be_received_.front();
+  RewrittenMessage& current = *locked_data_.to_be_received_.front();
 
-  int retval = current->Read(msg);
+  int retval = current.Read(msg);
 
-  // When a message is entirely consumed, remove if from the waiting queue.
-  if (current->is_consumed())
+  // When a message is entirely consumed, remove it from the waiting queue.
+  if (current.is_consumed())
     locked_data_.to_be_received_.pop();
 
   return retval;
@@ -826,8 +822,9 @@ void NaClIPCAdapter::SendMessageOnIOThread(
   io_thread_data_.channel_->Send(message.release());
 }
 
-void NaClIPCAdapter::SaveMessage(const IPC::Message& msg,
-                                 RewrittenMessage* rewritten_msg) {
+void NaClIPCAdapter::SaveMessage(
+    const IPC::Message& msg,
+    std::unique_ptr<RewrittenMessage> rewritten_msg) {
   lock_.AssertAcquired();
   // There is some padding in this structure (the "padding" member is 16
   // bits but this then gets padded to 32 bits). We want to be sure not to
@@ -842,7 +839,7 @@ void NaClIPCAdapter::SaveMessage(const IPC::Message& msg,
   header.num_fds = static_cast<uint16_t>(rewritten_msg->desc_count());
 
   rewritten_msg->SetData(header, msg.payload(), msg.payload_size());
-  locked_data_.to_be_received_.push(rewritten_msg);
+  locked_data_.to_be_received_.push(std::move(rewritten_msg));
 }
 
 int TranslatePepperFileReadWriteOpenFlagsForTesting(int32_t pp_open_flags) {