Clean up public interface of AttachmentBrokerUnprivileged.

In the old interface, a static factory method returns a scoped_ptr, and the
caller had to manage the lifetime. Since this is a global object with minimal
memory footprint, and is required to outlive every IPC::Channel, it's much
easier for the global to never be destroyed. This also matches the interface for
AttachmentBrokerPrivileged.

BUG=584297

Review URL: https://codereview.chromium.org/1679763002

Cr-Commit-Position: refs/heads/master@{#375674}

1 files changed, 8 insertions, 10 deletions

diff --git a/ipc/attachment_broker_unprivileged.h b/ipc/attachment_broker_unprivileged.h
index b572ff8..f6d520d 100644
--- a/ipc/attachment_broker_unprivileged.h
+++ b/ipc/attachment_broker_unprivileged.h
@@ -22,17 +22,15 @@ class IPC_EXPORT AttachmentBrokerUnprivileged : public IPC::AttachmentBroker {
   AttachmentBrokerUnprivileged();
   ~AttachmentBrokerUnprivileged() override;
 
-   // On platforms that support attachment brokering, returns a new instance of
-   // a platform-specific attachment broker. Otherwise returns |nullptr|.
-   // The caller takes ownership of the newly created instance, and is
-   // responsible for ensuring that the attachment broker lives longer than
-   // every IPC::Channel. The new instance automatically registers itself as the
-   // global attachment broker.
-  static scoped_ptr<AttachmentBrokerUnprivileged> CreateBroker();
+  // If there is no global attachment broker, makes a new
+  // AttachmentBrokerUnprivileged and sets it as the global attachment broker.
+  // This method is thread safe.
+  static void CreateBrokerIfNeeded();
 
-  // In each unprivileged process, exactly one channel should be used to
-  // communicate brokerable attachments with the broker process.
-  void DesignateBrokerCommunicationChannel(Endpoint* endpoint);
+  // AttachmentBroker:
+  void RegisterBrokerCommunicationChannel(Endpoint* endpoint) override;
+  void DeregisterBrokerCommunicationChannel(Endpoint* endpoint) override;
+  bool IsPrivilegedBroker() override;
 
  protected:
   IPC::Sender* get_sender() { return sender_; }