Add FakeComponentContext implementation for new API ConnectToAgentService

Add a basic FakeComponentContext implementation of ConnectToAgentService
to be used for Unit Testing.

Bug: b/139953375
Change-Id: I68fa278c5fb287eda691ab30ca21fa6381b93717
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1770955
Commit-Queue: Haines Sy <hainesy@google.com>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#690904}

fuchsia/base/fake_component_context.cc

@@ -32,6 +32,15 @@ void FakeComponentContext::ConnectToAgent(
   agent_impl_.Connect(component_url_, std::move(services));
 }
 
+void FakeComponentContext::ConnectToAgentService(
+    fuchsia::modular::AgentServiceRequest request) {
+  if (!agent_services_) {
+    ConnectToAgent(component_url_, agent_services_.NewRequest(), nullptr);
+  }
+  agent_services_->ConnectToService(std::move(request.service_name()),
+                                    std::move(*request.mutable_channel()));
+}
+
 void FakeComponentContext::NotImplemented_(const std::string& name) {
   NOTIMPLEMENTED() << " API: " << name;
 }

fuchsia/base/fake_component_context.h

@@ -37,6 +37,8 @@ class FakeComponentContext
       fidl::InterfaceRequest<::fuchsia::sys::ServiceProvider> services,
       fidl::InterfaceRequest<fuchsia::modular::AgentController> controller)
       override;
+  void ConnectToAgentService(
+      fuchsia::modular::AgentServiceRequest request) override;
   void NotImplemented_(const std::string& name) override;
 
  private:
@@ -44,6 +46,7 @@ class FakeComponentContext
       binding_;
   AgentImpl agent_impl_;
   const std::string component_url_;
+  fuchsia::sys::ServiceProviderPtr agent_services_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeComponentContext);
 };