Implement a module system for the extension bindings JS.

chrome/renderer/resources/extensions/setup_bindings.js

+// Copyright (c) 2012 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.
+
+// Set up the global chrome object.
+chrome = {};
+
+var contextInfo = requireNative('context_info');
+var sgb = requireNative('schema_generated_bindings');
+
+require('app');

[Aaron Boodman, 2012/03/01 07:24:26]

Why do this in JavaScript? It seems to end up being more complex than just doing
it here in C++. Control passes from C++ to a static chunk of JS, back into C++.
It also requires the ContextInfo native.

[koz (OOO until 15th September), 2012/03/02 01:13:58]

I think it makes it easier to understand what's happening this way - all the
code that sets up bindings happens in setup_bindings.js. Better to set up some
native handlers, then jump in to JS to do the rest of the job than to have C++
require various JS files, which is a C++/JS dance anyway.

Besides, this may not always be so trivial. Right now all this file does is
require() a bunch of modules that perform work as a side-effect, but ideally
modules don't perform any work when they are require()d and it would be the
responsibility of this file to invoke the schema generation explicitly, which
would be much harder to do in C++ than in JS.

+require('webstore');
+
+if (contextInfo.IsBindingsAllowed()) {
+  require('json_schema');

[Aaron Boodman, 2012/03/01 07:24:26]

Have schema_generated_bindings just require this?

[koz (OOO until 15th September), 2012/03/02 01:13:58]

Done.

+  require('event_bindings');

[Aaron Boodman, 2012/03/01 07:24:26]

Have miscellaneous_bindings and schema_generated_bindings each require this?

[koz (OOO until 15th September), 2012/03/02 01:13:58]

Done.

+  require('miscellaneous_bindings');
+  require('schema_generated_bindings');
+  require('apitest');
+
+  // Load the custom bindings for each API.
+  sgb.GetExtensionAPIDefinition().forEach(function(apiDef) {

[Aaron Boodman, 2012/03/01 07:24:26]

I wonder if this could be part of SchemaGeneratedBindings. For each module, try
to load a custom bindings file for it.

[koz (OOO until 15th September), 2012/03/02 01:13:58]

Yeah, it could be, but with this change I'd rather it be isomorphic to how it
works currently. Right now setup_bindings.js mirrors what happens with the
current v8::Extension based thing: load some modules which set things in
chromeHidden, then for each custom binding we check if we can inject that too,
then we dispatch an onLoad() event from C++ to have the generation actually
occur.

Right now there's no need to set things up as listeners on onLoad() as all this
code can be run synchronously, but I think that would be better as its own
isolated change.

+    if (contextInfo.IsAPIAllowed(apiDef.namespace))
+      require(apiDef.namespace);
+  });
+}