Use WeakBindingSet to manage inspector connections

mojo/public/cpp/bindings/binding.h

Index: mojo/public/cpp/bindings/binding.h
diff --git a/mojo/public/cpp/bindings/binding.h b/mojo/public/cpp/bindings/binding.h
index 2c4c9ceb05dc2ecc838b5b11d59252adafdd497f..080d62eebd87d012615476ee60b1a41944bd21f4 100644
--- a/mojo/public/cpp/bindings/binding.h
+++ b/mojo/public/cpp/bindings/binding.h
@@ -34,7 +34,6 @@ namespace mojo {
 //    private:
 //     Binding<Foo> binding_;
 //   };
-//
 template <typename Interface>
 class Binding : public ErrorHandler {
  public:
@@ -106,6 +105,11 @@ class Binding : public ErrorHandler {
     return internal_router_->WaitForIncomingMessage();
   }
 
+  void Close() {
+    MOJO_DCHECK(internal_router_);
+    internal_router_->CloseMessagePipe();
+  }
+
   void set_error_handler(ErrorHandler* error_handler) {
     error_handler_ = error_handler;
   }