Introduce InterfaceEndpointClient(IEC), InterfaceEndpointHandle and

mojo/public/js/lib/interface_endpoint_handle.js

+// Copyright 2017 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.
+
+define("mojo/public/js/lib/interface_endpoint_handle", [
+  "mojo/public/js/interface_types",
+  "timer",
+], function(types, timer) {
+
+  var AssociationEvent = {
+    // The interface has been associated with a message pipe.
+    ASSOCIATED: 'associated',
+    // The peer of this object has been closed before association.
+    PEER_CLOSED_BEFORE_ASSOCIATION: 'peer_closed_before_association'
+  };
+
+  function State(interfaceId, associatedGroupController) {
+    if (interfaceId === undefined) {
+      interfaceId = types.kInvalidInterfaceId

[yzshen1, 2017/03/24 21:20:13]

trailing ";"

[wangjimmy, 2017/03/27 16:51:28]

Done.

+    }
+
+    this.interfaceId = interfaceId;
+    this.associatedGroupController = associatedGroupController;
+    this.pendingAssociation = false;
+    this.disconnectReason = null;
+    this.peerState_ = null;
+    this.associationEventHandler_ = undefined;
+  }
+
+  State.prototype.initPendingState = function(peer) {
+    this.pendingAssociation = true;
+    this.peerState_ = peer;
+  };
+
+  State.prototype.isValid = function() {
+    return this.pendingAssociation ||
+        types.isValidInterfaceId(this.interfaceId);
+  };
+
+  State.prototype.close = function(disconnectReason) {

[yzshen1, 2017/03/24 21:20:13]

Please also reset associationEventHandler_, interfaceId, pendingAssociation,
peerState as needed.

[wangjimmy, 2017/03/27 16:51:28]

Done.

+    if (this.associatedGroupController) {
+      this.associatedGroupController.closeEndpointHandle(this.interfaceId,
+          disconnectReason);
+    } else if (this.peerState_) {
+      this.peerState_.onPeerClosedBeforeAssociation(disconnectReason);
+    }
+  };
+
+  State.prototype.runAssociationEventHandler = function(associationEvent) {
+    function run() {
+      this.associationEventHandler_(associationEvent);
+      this.associationEventHandler_ = undefined;

[yzshen1, 2017/03/24 21:20:13]

Although it shouldn't matter in this particular case, it is generally a good
practice to assign this handler to a local variable and set it to undefined, and
then run the handler.

That way if the handler does something resulting in a new
this.associationEventHandler_ to be set. It won't be reset to undefined
afterwards unintentionally.

[wangjimmy, 2017/03/27 16:51:28]

Done, changed it. Since you're right a callback could set the handler. Doesn't
happen in this case, but still good practice to follow. Thanks!

+    }
+
+    if (this.associationEventHandler_) {
+      timer.createOneShot(0, run.bind(this));

[yzshen1, 2017/03/24 21:20:13]

At the time when run() is run, this.asssociationEventHandler_ may have been
reset.

Therefore, the "if (this.associationEventHandler_)" check should be done inside
run() instead.

[wangjimmy, 2017/03/27 16:51:28]

Done.

+    }
+  };
+
+  State.prototype.setAssociationEventHandler = function(handler) {
+    if ((!this.pendingAssociation &&
+         !types.isValidInterfaceId(this.interfaceId)) || !handler) {

[yzshen1, 2017/03/24 21:20:13]

If handler is null, you need to reset this.associationEventHandler_.

[wangjimmy, 2017/03/27 16:51:28]

Done.

+      return;
+    }
+
+    this.associationEventHandler_ = handler;
+    if (!this.pendingAssociation) {
+      this.runAssociationEventHandler(AssociationEvent.ASSOCIATED);
+    } else if (!this.peerState_) {
+      this.runAssociationEventHandler(
+          AssociationEvent.PEER_CLOSED_BEFORE_ASSOCIATION);
+    }
+  };
+
+  State.prototype.onAssociated = function(interfaceId,
+      associatedGroupController) {
+    if (!this.pendingAssociation) {
+      return;
+    }
+
+    this.pendingAssociation = false;
+    this.peerState_ = null;
+    this.interfaceId = interfaceId;
+    this.associatedGroupController = associatedGroupController;
+    this.runAssociationEventHandler(AssociationEvent.ASSOCIATED);

[yzshen1, 2017/03/24 21:20:13]

We have to run the handler immediately instead of delay it with a timer in this
case. The reason:

FooAssociatedPtr foo_ptr;
FooAssociatedRequest request = makeRequest(foo_ptr);

another_ptr.sendFooRequest(request);

// At this point, we must have already notified foo_ptr about the association,
otherwise you cannot use foo_ptr immediately.
foo_ptr.callMethod();

[wangjimmy, 2017/03/27 16:51:28]

Done.

+  };
+
+  State.prototype.onPeerClosedBeforeAssociation = function(disconnectReason) {
+    if (!this.pendingAssociation) {
+      return;
+    }
+
+    this.peerState_ = null;
+    this.disconnectReason = disconnectReason;
+
+    this.runAssociationEventHandler(

[yzshen1, 2017/03/24 21:20:13]

Run the handler immediately instead of delaying it with a timer. In IEC you will
delay the notification to the user with a timer already, so no need to do it
twice.

[wangjimmy, 2017/03/27 16:51:28]

Done.

+        AssociationEvent.PEER_CLOSED_BEFORE_ASSOCIATION);
+  };
+
+  function InterfaceEndpointHandle(interfaceId, associatedGroupController) {
+    this.state_ = new State(interfaceId, associatedGroupController);
+  }
+
+  InterfaceEndpointHandle.prototype.isValid = function() {
+    return this.state_.isValid();
+  };
+
+  InterfaceEndpointHandle.prototype.pendingAssociation = function() {
+    return this.state_.pendingAssociation;
+  };
+
+  InterfaceEndpointHandle.prototype.id = function() {
+    return this.state_.interfaceId;
+  };
+
+  InterfaceEndpointHandle.prototype.groupController = function() {
+    return this.state_.associatedGroupController;
+  };
+
+  InterfaceEndpointHandle.prototype.disconnectReason = function() {
+    return this.state_.disconnectReason;
+  };
+
+  InterfaceEndpointHandle.prototype.setAssociationEventHandler = function(
+      handler) {
+    this.state_.setAssociationEventHandler(handler);
+  };
+
+  InterfaceEndpointHandle.prototype.reset = function(reason) {
+    this.state_.close(reason);
+    this.state_ = new State();
+  };
+
+  var exports = {};
+  exports.InterfaceEndpointHandle = InterfaceEndpointHandle;
+
+  return exports;
+});