Dart: Simplifies the handle watcher. Various cleanups and bugfixes.

mojo/public/tools/bindings/generators/dart_templates/interface_definition.tmpl

 {%- for method in interface.methods %}
 const int k{{interface.name}}_{{method.name}}_name = {{method.ordinal}};
 {%- endfor %}
 
 abstract class {{interface.name}}Calls {
   void enqueueMessage(Type t, int name, Object msg);
   Future enqueueMessageWithRequestID(Type t, int name, int id, Object msg);
   bool get isOpen;
 
 {%- for method in interface.methods %}
 {%- if method.response_parameters == None %}
   void call{{method.name}}(
 {%- for parameter in method.parameters -%}
     {{parameter.kind|dart_decl_type}} {{parameter.name}}{% if not loop.last %}, {% endif %}
 {%- endfor -%}
   ) {
     assert(isOpen);
     var params = new {{interface.name}}_{{method.name}}_Params();
 {%- for parameter in method.parameters %}
     params.{{parameter.name}} = {{parameter.name}};
 {%- endfor %}
     enqueueMessage({{interface.name}}_{{method.name}}_Params,
                    k{{interface.name}}_{{method.name}}_name,
                    params);
   }
 {% else %}
   Future<{{interface.name}}_{{method.name}}_ResponseParams> call{{method.name}}(
 {%- for parameter in method.parameters -%}
-    {{parameter.kind|dart_decl_type}} {{parameter.name}}{% if not loop.last %}, {% endif %}
+    {{parameter.kind|dart_decl_type}} {{parameter.name}},
 {%- endfor -%}
+    [int requestId = -1]
   ) {
     assert(isOpen);
     var params = new {{interface.name}}_{{method.name}}_Params();
 {%- for parameter in method.parameters %}
     params.{{parameter.name}} = {{parameter.name}};
 {%- endfor %}
     return enqueueMessageWithRequestID(
         {{interface.name}}_{{method.name}}_Params,
         k{{interface.name}}_{{method.name}}_name,
-        0,
+        requestId,
         bindings.kMessageExpectsResponse,
         params);
   }
 {%- endif %}
 {%- endfor %}
 }
 
 class {{interface.name}}Client extends bindings.Client with {{interface.name}}Calls {
   {{interface.name}}Client(core.MojoMessagePipeEndpoint endpoint) : super(endpoint);
 
+  {{interface.name}}Client.fromHandle(int handle) : super.fromHandle(handle);
+
   void handleResponse(bindings.MessageReader reader) {
     switch (reader.name) {
 {%- for method in interface.methods %}
 {%- if method.response_parameters != None %}
       case k{{interface.name}}_{{method.name}}_name:
         var r = reader.decodeStruct({{interface.name}}_{{method.name}}_ResponseParams);
-        Completer c = completerQueue.removeAt(0);
+        Completer c = completerMap[reader.requestID];
+        completerMap[reader.requestID] = null;
         c.complete(r);
         break;
 {%- endif %}
 {%- endfor %}
       default:
         throw new Exception("Unexpected message name");
         break;
     }
   }
 }
 
 
 abstract class {{interface.name}}Interface extends bindings.Interface
 {% if interface.client != None -%}
 with {{imported_from[interface.client]}}{{interface.client}}Calls
 {% endif -%} {
   {{interface.name}}Interface(core.MojoMessagePipeEndpoint endpoint) : super(endpoint);
 
+  {{interface.name}}Interface.fromHandle(int handle) : super.fromHandle(handle);
+
+  static const String name = '{{namespace|replace(".","::")}}::{{interface.name}}';
+
 {% for method in interface.methods %}
 {%- if method.response_parameters == None %}
   void {{method.name|stylize_method}}(
   {%- for parameter in method.parameters -%}
     {{parameter.kind|dart_decl_type}} {{parameter.name}}{% if not loop.last %}, {% endif %}
   {%- endfor -%}
   );
 {%- else %}
   {{interface.name}}_{{method.name}}_ResponseParams {{method.name|stylize_method}}(
   {%- for parameter in method.parameters -%}
     {{parameter.kind|dart_decl_type}} {{parameter.name}}{% if not loop.last %}, {% endif %}
   {%- endfor -%}
   );
 {%- endif %}
 {%- endfor %}
 
-  bindings.Message handleMessage(bindings.MessageReader reader) {
+  Future<bindings.Message> handleMessage(bindings.MessageReader reader) {
     switch (reader.name) {
 {%- for method in interface.methods %}
       case k{{interface.name}}_{{method.name}}_name:
         var params = reader.decodeStruct({{interface.name}}_{{method.name}}_Params);
 {%- if method.response_parameters == None %}
-        {{method.name|stylize_method}}(params);
-{%- else %}
-        var response = {{method.name|stylize_method}}(
+        {{method.name|stylize_method}}(
           {%- for parameter in method.parameters -%}
               params.{{parameter.name}}{% if not loop.last %}, {% endif %}
           {%- endfor -%}
         );
-        return buildResponseWithID(
-            {{interface.name}}_{{method.name}}_ResponseParams,
-            k{{interface.name}}_{{method.name}}_name,
-            reader.requestID,
-            bindings.kMessageIsResponse,
-            response);
+{%- else %}
+        return {{method.name|stylize_method}}(
+          {%- for parameter in method.parameters -%}
+              params.{{parameter.name}}{% if not loop.last %}, {% endif %}
+          {%- endfor -%}
+        ).then((response) {
+          if (response != null) {
+            return buildResponseWithID(
+                {{interface.name}}_{{method.name}}_ResponseParams,
+                k{{interface.name}}_{{method.name}}_name,
+                reader.requestID,
+                bindings.kMessageIsResponse,
+                response);
+          }
+        });
 {%- endif %}
         break;
 {%- endfor %}
       default:
         throw new Exception("Unexpected message name");
         break;
     }
     return null;
   }
 }
 
 
 {#--- TODO(zra): Validation #}
 
 
 {#--- Interface Constants #}
 {% for constant in interface.constants %}
 final {{constant.name}} = {{constant.value|expression_to_text}};
 {%-   endfor %}
 
 
 {#--- Interface Enums #}
 {%- from "enum_definition.tmpl" import enum_def -%}
 {%- for enum in interface.enums %}
   {{ enum_def("", enum) }}
 {%-  endfor %}