[Extensions Bindings] Add Events support

extensions/renderer/api_binding.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 EXTENSIONS_RENDERER_API_BINDING_H_
 #define EXTENSIONS_RENDERER_API_BINDING_H_
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/supports_user_data.h"
 #include "extensions/renderer/argument_spec.h"
 #include "v8/include/v8.h"
 
 namespace base {
 class ListValue;
 }
 
 namespace gin {
 class Arguments;
 }
 
 namespace extensions {
+class APIEventHandler;
 
 // A class that vends v8::Objects for extension APIs. These APIs have function
 // interceptors for all exposed methods, which call back into the APIBinding.
 // The APIBinding then matches the calling arguments against an expected method
 // signature, throwing an error if they don't match.
 // There should only need to be a single APIBinding object for each API, and
 // each can vend multiple v8::Objects for different contexts.
 // TODO(devlin): What's the lifetime of this object?
 class APIBinding {
  public:
   // The callback to called when an API method is invoked with matching
   // arguments. This passes the name of the api method and the arguments it
   // was passed, as well as the current isolate, context, and callback value.
   // Note that the callback can be empty if none was passed.
   using APIMethodCallback =
       base::Callback<void(const std::string& name,
                           std::unique_ptr<base::ListValue> arguments,
                           v8::Isolate*,
                           v8::Local<v8::Context>,
                           v8::Local<v8::Function>)>;
 
   // The callback for determining if a given API method (specified by |name|)
   // is available.
   using AvailabilityCallback = base::Callback<bool(const std::string& name)>;
 
   // The callback type for handling an API call.
   using HandlerCallback = base::Callback<void(gin::Arguments*)>;
 
   // The ArgumentSpec::RefMap is required to outlive this object.
-  // |type_definitions| may be null if the API does not specify any types.
+  // |type_definitions| and |event_definitions| may be null if the API does not
+  // specify any types or events.
   APIBinding(const std::string& name,
              const base::ListValue& function_definitions,
              const base::ListValue* type_definitions,
+             const base::ListValue* event_definitions,
              const APIMethodCallback& callback,
              ArgumentSpec::RefMap* type_refs);
   ~APIBinding();
 
   // Returns a new v8::Object for the API this APIBinding represents.
   v8::Local<v8::Object> CreateInstance(
       v8::Local<v8::Context> context,
       v8::Isolate* isolate,
+      APIEventHandler* event_handler,
       const AvailabilityCallback& is_available);
 
  private:
   using APISignature = std::vector<std::unique_ptr<ArgumentSpec>>;
 
   // Per-context data that stores the callbacks that are used within the
   // context. Since these callbacks are used within v8::Externals, v8 itself
   // does not clean them up.
   struct APIPerContextData : public base::SupportsUserData::Data {
     APIPerContextData();
     ~APIPerContextData() override;
 
     std::vector<std::unique_ptr<HandlerCallback>> context_callbacks;
   };
 
   // Handles a call an API method with the given |name| and matches the
   // arguments against |signature|.
   void HandleCall(const std::string& name,
                   const APISignature* signature,
                   gin::Arguments* args);
 
   // The root name of the API, e.g. "tabs" for chrome.tabs.
   std::string api_name_;
 
   // A map from method name to expected signature.
   std::map<std::string, std::unique_ptr<APISignature>> signatures_;
 
+  // The names of all events associated with this API.
+  std::vector<std::string> event_names_;
+
   // The callback to use when an API is invoked with valid arguments.
   APIMethodCallback method_callback_;
 
   // The reference map for all known types; required to outlive this object.
   const ArgumentSpec::RefMap* type_refs_;
 
   base::WeakPtrFactory<APIBinding> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(APIBinding);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_API_BINDING_H_