[chromecast] Enable Mojo javascript bindings for cast_shell

chromecast/renderer/cast_gin_runner.h

+// Copyright 2016 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 CHROMECAST_RENDERER_CAST_GIN_RUNNER_H_
+#define CHROMECAST_RENDERER_CAST_GIN_RUNNER_H_
+
+#include "base/macros.h"
+#include "gin/runner.h"
+
+namespace blink {
+class WebFrame;
+}
+
+namespace chromecast {
+namespace shell {
+
+// This class is an exact copy of content::MojoMainRunner used to replicate

[Ken Rockot(use gerrit already), 2016/09/14 21:13:22]

nit: This documentation is probably unnecessary and is likely to become stale.
We're eventually going to move away from using gin (and I suspect cast may want
to as well, but that's a separate concern) and these classes will diverge.

[alokp, 2016/09/14 21:55:36]

Yes we will move away from gin as well. In fact we are planning to bundle
mojo-js public API with cast SDK. At that point I wonder what gin dependencies
will remain.

[jarhar, 2016/09/15 00:32:42]

Done.

+// logic for enabling a Mojo API in JavaScript for Chromecast.
+
+// Implementation of gin::Runner that forwards Runner functions to WebFrame.
+class CastGinRunner : public gin::Runner {
+ public:
+  // Does not take ownership of ContextHolder.
+  CastGinRunner(blink::WebFrame* frame, gin::ContextHolder* context_holder);
+  ~CastGinRunner() override {}
+
+  // Runner overrides:
+  void Run(const std::string& source,
+           const std::string& resource_name) override;
+  v8::Local<v8::Value> Call(v8::Local<v8::Function> function,
+                            v8::Local<v8::Value> receiver,
+                            int argc,
+                            v8::Local<v8::Value> argv[]) override;
+  gin::ContextHolder* GetContextHolder() override;
+
+ private:
+  // Frame to execute script in.
+  blink::WebFrame* frame_;

[derekjchow1, 2016/09/14 21:20:13]

Can this be blink::WebFrame* const frame_?

[jarhar, 2016/09/15 00:32:42]

Done.

+
+  // Created by blink bindings to V8.
+  gin::ContextHolder* context_holder_;

[derekjchow1, 2016/09/14 21:20:14]

Ditto. Should this variable change over the object lifetime?

[jarhar, 2016/09/15 00:32:42]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(CastGinRunner);
+};
+
+}  // namespace shell
+}  // namespace chromecast
+
+#endif  // CHROMECAST_RENDERER_CAST_GIN_RUNNER_H_