ipc: Move AttachmentBrokerPrivileged singleton logic into ipc/.

ipc/attachment_broker.h

Index: ipc/attachment_broker.h
diff --git a/ipc/attachment_broker.h b/ipc/attachment_broker.h
index 8e00ffb597cc4a8e2c58fe8a7c79163a6c59816c..36489d4ee9dc8133e7184aceec9cb31e19152a9f 100644
--- a/ipc/attachment_broker.h
+++ b/ipc/attachment_broker.h
@@ -22,12 +22,6 @@
 #define USE_ATTACHMENT_BROKER 0
 #endif  // defined(OS_WIN)
 
-#if defined(OS_MACOSX) && !defined(OS_IOS)
-namespace base {
-class PortProvider;
-}  // namespace base
-#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
-
 namespace IPC {
 
 class AttachmentBroker;
@@ -92,17 +86,6 @@ class IPC_EXPORT AttachmentBroker : public Listener {
   virtual void RegisterCommunicationChannel(Endpoint* endpoint);
   virtual void DeregisterCommunicationChannel(Endpoint* endpoint);
 
-#if defined(OS_MACOSX) && !defined(OS_IOS)
-  // This method should only be called by the broker process.
-  //
-  // The port provider must live as long as the AttachmentBroker. A port
-  // provider must be set before any attachment brokering occurs.
-  void set_port_provider(base::PortProvider* port_provider) {
-    DCHECK(!port_provider_);
-    port_provider_ = port_provider;
-  }
-#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
-
  protected:
   using AttachmentVector = std::vector<scoped_refptr<BrokerableAttachment>>;
 
@@ -116,10 +99,6 @@ class IPC_EXPORT AttachmentBroker : public Listener {
   // This method is exposed for testing only.
   AttachmentVector* get_attachments() { return &attachments_; }
 
-#if defined(OS_MACOSX) && !defined(OS_IOS)
-  base::PortProvider* port_provider() const { return port_provider_; }
-#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
-
  private:
 #if defined(OS_WIN)
   FRIEND_TEST_ALL_PREFIXES(AttachmentBrokerUnprivilegedWinTest,
@@ -128,10 +107,6 @@ class IPC_EXPORT AttachmentBroker : public Listener {
                            ReceiveInvalidMessage);
 #endif  // defined(OS_WIN)
 
-#if defined(OS_MACOSX) && !defined(OS_IOS)
-  base::PortProvider* port_provider_;
-#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
-
   // A vector of BrokerableAttachments that have been received, but not yet
   // consumed.
   // A std::vector is used instead of a std::map because this container is