Make Service own ServiceContext.

mash/browser/browser.h

Index: mash/browser/browser.h
diff --git a/mash/browser/browser.h b/mash/browser/browser.h
index 7a4271b6adbfabd7daba0d6920ae053d9708ae2d..5a38100d714e10e9f1a0d9f1d7ea9dd0ab88c5dc 100644
--- a/mash/browser/browser.h
+++ b/mash/browser/browser.h
@@ -43,9 +43,7 @@ class Browser : public shell::Service,
 
  private:
   // shell::Service:
-  void OnStart(shell::Connector* connector,
-               const shell::Identity& identity,
-               uint32_t id) override;
+  void OnStart(const shell::Identity& identity) override;
   bool OnConnect(shell::Connection* connection) override;
 
   // mojom::Launchable:
@@ -55,7 +53,6 @@ class Browser : public shell::Service,
   void Create(const shell::Identity& remote_identity,
               mojom::LaunchableRequest request) override;
 
-  shell::Connector* connector_ = nullptr;
   mojo::BindingSet<mojom::Launchable> bindings_;
   std::vector<views::Widget*> windows_;