Adding a bound accessor to service_manager::Connector.

Adding a bound accessor to service_manager::Connector so clients that
require a fresh (unbound) connector can check that.

Bug: None
Change-Id: I555e32b71d7259713544f6283c8868827409382c
Reviewed-on: https://chromium-review.googlesource.com/803907Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Jay Civelli <jcivelli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521048}

services/service_manager/public/cpp/connector.cc

@@ -95,6 +95,10 @@ std::unique_ptr<Connector> Connector::Clone() {
   return std::make_unique<Connector>(connector.PassInterface());
 }
 
+bool Connector::IsBound() const {
+  return connector_.is_bound();
+}
+
 void Connector::FilterInterfaces(const std::string& spec,
                                  const Identity& source_identity,
                                  mojom::InterfaceProviderRequest request,

services/service_manager/public/cpp/connector.h

@@ -131,6 +131,9 @@ class SERVICE_MANAGER_PUBLIC_CPP_EXPORT Connector {
   // to pass again.
   std::unique_ptr<Connector> Clone();
 
+  // Returns true if this Connector instance is already bound to a thread.
+  bool IsBound() const;
+
   void FilterInterfaces(const std::string& spec,
                         const Identity& source_identity,
                         mojom::InterfaceProviderRequest request,