Mojo JS bindings: make sure that console.log() could be used in the bindings.

ios/web/webui/mojo_facade.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 IOS_WEB_WEBUI_MOJO_FACADE_H_
 #define IOS_WEB_WEBUI_MOJO_FACADE_H_
 
 #include <map>
 #include <string>
 
@@ skipping 32 matching lines @@
   // a string representing the name of Mojo message and "args" is a dictionary
   // with arguments specific for each message name.
   // Supported message names with their handler methods in parenthesis:
   //   interface_provider.getInterface (HandleInterfaceProviderGetInterface)
   //   core.close (HandleCoreClose)
   //   core.createMessagePipe (HandleCoreCreateMessagePipe)
   //   core.writeMessage (HandleCoreWriteMessage)
   //   core.readMessage (HandleCoreReadMessage)
   //   support.watch (HandleSupportWatch)
   //   support.cancelWatch (HandleSupportCancelWatch)
+  //   console.log (HandleConsoleLog)
   std::string HandleMojoMessage(const std::string& mojo_message_as_json);
 
  private:
   // Extracts message name and arguments from the given JSON string obtained
   // from WebUI page. This method either succeeds or crashes the app (this
   // matches other platforms where Mojo API is strict on malformed input).
   void GetMessageNameAndArguments(
       const std::string& mojo_message_as_json,
       std::string* out_name,
       std::unique_ptr<base::DictionaryValue>* out_args);
@@ skipping 55 matching lines @@
   std::unique_ptr<base::Value> HandleSupportWatch(
       const base::DictionaryValue* args);
 
   // Cancels a handle watch initiated by "support.watch". |args| is a dictionary
   // which must contain "watchId" key (a number representing id returned from
   // "support.watch").
   // Returns null.
   std::unique_ptr<base::Value> HandleSupportCancelWatch(
       const base::DictionaryValue* args);
 
+  // Logs a message. |args| is a dictionary which must contain "message" key.
+  // Returns null.
+  std::unique_ptr<base::Value> HandleConsoleLog(
+      const base::DictionaryValue* args);
+
   // Provides interfaces.
   service_manager::mojom::InterfaceProvider* interface_provider_;
   // Runs JavaScript on WebUI page.
   base::WeakNSProtocol<id<CRWJSInjectionEvaluator>> script_evaluator_;
   // Id of the last created watch.
   int last_watch_id_;
   // Currently active watches created through this facade.
   std::map<int, mojo::Watcher> watchers_;
 };
 
 }  // web
 
 #endif  // IOS_WEB_WEBUI_MOJO_FACADE_H_