Mojo JS Bindings: Simplify sharing services for content-provided JS applications

mojo/apps/js/js_app.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_APPS_JS_JS_APP_H_
 #define MOJO_APPS_JS_JS_APP_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread.h"
 #include "gin/public/isolate_holder.h"
@@ skipping 20 matching lines @@
   bool Start();
 
   // Subclasses must return the JS source code for this app's main script and
   // the filename or URL that identifies the script's origin. This method will
   // be called from this app's thread.
   virtual bool Load(std::string* source, std::string* file_name) = 0;
 
   // Called by the JS mojo module to quit this JS app. See mojo.js.
   void Quit();
 
-  // Called by the JS mojo module to connect to a Mojo service.
-  Handle ConnectToService(const std::string& application_url,
-                          const std::string& interface_name);
+  // Called by the JS mojo module to connect to a Mojo application.
+  Handle ConnectToApplication(const std::string& application_url);
+
+  // Called by the JS mojo module to retrieve the ServiceProvider message
+  // pipe handle passed to the JS content handler's OnConnect() method.
+  // If this app was not launched by the content handler then return a null
+  // Mojo handle.

[Aaron Boodman, 2014/10/24 22:17:18]

s/null/invalid/

[hansmuller, 2014/10/27 22:43:22]

In JS, invalid handles are mapped to null. I thought "invalid handle" could be
misleading although it's technically correct. What do you think?

[Aaron Boodman, 2014/10/29 17:12:51]

Well, this code is C++. So I feel like it should use C++ terminology. Conversion
between JS/C++ should ideally be isolated to one place in the code... ideally
just the gin::Converter specializations.

Also, I probably brought this up before, but could we create a Gin converter for
ScopedHandles and even the higher-level C++ types like InterfacePtr<T> so that
this code could be more self-documenting?

[hansmuller, 2014/10/29 22:43:40]

Done.

[hansmuller, 2014/10/29 22:43:40]

I did add a converter for MessagePipeHandle. I wasn't able to sort out how to
get Bind() to generate a callback that returned a scoped handle.

+  virtual Handle RequestorMessagePipeHandle() = 0;
 
  private:
   void Run();
   void Terminate();
 
   // Used to CHECK that we're running on the correct thread.
   bool on_app_delegate_impl_thread() const;
   bool on_js_app_thread() const;
 
   ApplicationDelegateImpl* app_delegate_impl_;
   base::Thread thread_;
   scoped_refptr<base::SingleThreadTaskRunner> app_delegate_impl_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> js_app_task_runner_;
   MojoRunnerDelegate runner_delegate_;
   scoped_ptr<gin::IsolateHolder> isolate_holder_;
   scoped_ptr<gin::ShellRunner> shell_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(JSApp);
 };
 
 }  // namespace apps
 }  // namespace mojo
 
 #endif  // MOJO_APPS_JS_JS_APP_H_