chromeos: Introduce SetClient() on ash::mojom::SystemTray interface

ash/common/system/tray/system_tray_controller.h

Index: ash/common/system/tray/system_tray_controller.h
diff --git a/ash/common/system/tray/system_tray_controller.h b/ash/common/system/tray/system_tray_controller.h
index 2cfb8bf87985498753d88d23c62e37d78db7ee8e..9abe99a68ce7131c04f6665a2e86667dca7f0791 100644
--- a/ash/common/system/tray/system_tray_controller.h
+++ b/ash/common/system/tray/system_tray_controller.h
@@ -12,29 +12,21 @@
 #include "base/macros.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 
-namespace service_manager {
-class Connector;
-}
-
 namespace ash {
 
 // Both implements mojom::SystemTray and wraps the mojom::SystemTrayClient
-// interface. The wrapper makes the initial connection and handles reconnecting
-// on error. Implements both because it caches state pushed down from the
+// interface. Implements both because it caches state pushed down from the
 // browser process via SystemTray so it can be synchronously queried inside ash.
 //
 // Conceptually similar to historical ash-to-chrome interfaces like
 // SystemTrayDelegate. Lives on the main thread.
 //
-// Only connects to the actual mojom::SystemTrayClient interface when running on
-// Chrome OS. In tests and on Windows all operations are no-ops.
-//
 // TODO: Consider renaming this to SystemTrayClient or renaming the current
 // SystemTray to SystemTrayView and making this class SystemTray.
 class ASH_EXPORT SystemTrayController
     : NON_EXPORTED_BASE(public mojom::SystemTray) {
  public:
-  explicit SystemTrayController(service_manager::Connector* connector);
+  SystemTrayController();
   ~SystemTrayController() override;
 
   base::HourClockType hour_clock_type() const { return hour_clock_type_; }
@@ -64,19 +56,14 @@ class ASH_EXPORT SystemTrayController
   void BindRequest(mojom::SystemTrayRequest request);
 
  private:
-  // Connects or reconnects to the mojom::SystemTrayClient interface when
-  // running on Chrome OS. Otherwise does nothing. Returns true if connected.
-  bool ConnectToSystemTrayClient();
-
-  // Handles errors on the |system_tray_client_| interface connection.
-  void OnClientConnectionError();
+  // Returns true if |system_tray_client_| is bound. Otherwise logs an error and
+  // returns false.
+  bool HasSystemTrayClient();
 
   // mojom::SystemTray:
+  void SetClient(mojom::SystemTrayClientPtr client) override;
   void SetUse24HourClock(bool use_24_hour) override;
 
-  // May be null in unit tests.
-  service_manager::Connector* connector_;
-
   // Client interface in chrome browser. Only bound on Chrome OS.
   mojom::SystemTrayClientPtr system_tray_client_;