[FIX] web: InputField: don't re-render if dirty

Let's assume that we have a form view with a one2many field
displayed as a list containing two fields A and B (an input field,
e.g. a char field). An onchange on the one2many is triggered as
soon as A changes. This triggers a reset of the one2many which
thus redraws the corresponding line by resetting its widgets.

A problem occured when the user updated A, and directly (before
the onchange returned) updated the input field B, as in this case
the new value in B was erased when the onchanged returned, as the
widget was reset with its former value (or with the value returned
by the onchange, if any). Note that the model was aware of the
change on B, so the model and the UI were actually desynchronized.

This was quite hard to reproduce in practice, by hand, but it
occured in the tour testing 'the flow', in the form view of
account.bank_statement, with fields partner_id and amount of the
line_ids one2many.

With this rev., we don't re-render the input fields if there are
pending changes that haven't been acknowledged by the model.

addons/web/static/src/js/fields/basic_fields.js

@@ -151,6 +151,9 @@ var DebouncedField = AbstractField.extend({
 });
 
 var InputField = DebouncedField.extend({
+    custom_events: _.extend({}, DebouncedField.prototype.custom_events, {
+        field_changed: '_onFieldChanged',
+    }),
     events: _.extend({}, DebouncedField.prototype.events, {
         'input': '_onInput',
         'change': '_onChange',
@@ -168,6 +171,12 @@ var InputField = DebouncedField.extend({
         if (this.mode === 'edit') {
             this.tagName = 'input';
         }
+        // We need to know if the widget is dirty (i.e. if the user has changed
+        // the value, and those changes haven't been acknowledged yet by the
+        // environment), to prevent erasing that new value on a reset (e.g.
+        // coming by an onchange on another field)
+        this.isDirty = false;
+        this.lastChangeEvent = undefined;
     },
 
     //--------------------------------------------------------------------------
@@ -183,14 +192,21 @@ var InputField = DebouncedField.extend({
         return this.$input || $();
     },
     /**
-     * Do not re-render this field if it was the origin of the onchange call.
-     * FIXME: make the onchange work on itself without disturbing the user typing
+     * Re-renders the widget if it isn't dirty. The widget is dirty if the user
+     * changed the value, and that change hasn't been acknowledged yet by the
+     * environment. For example, another field with an onchange has been updated
+     * and this field is updated before the onchange returns. Two '_setValue'
+     * are done (this is sequential), the first one returns and this widget is
+     * reset. However, it has pending changes, so we don't re-render.
      *
      * @override
      */
     reset: function (record, event) {
         this._reset(record, event);
-        if (event && event.target === this) {
+        if (!event || event === this.lastChangeEvent) {
+            this.isDirty = false;
+        }
+        if (this.isDirty || (event && event.target === this)) {
             return $.when();
         } else {
             return this._render();
@@ -265,6 +281,16 @@ var InputField = DebouncedField.extend({
     _onChange: function () {
         this._doAction();
     },
+    /**
+     * Listens to events 'field_changed' to keep track of the last event that
+     * has been trigerred. This allows to detect that all changes have been
+     * acknowledged by the environment.
+     *
+     * @param {OdooEvent} event 'field_changed' event
+     */
+    _onFieldChanged: function (event) {
+        this.lastChangeEvent = event;
+    },
     /**
      * Called when the user is typing text -> By default this only calls a
      * debounced method to notify the outside world of the changes.
@@ -273,6 +299,7 @@ var InputField = DebouncedField.extend({
      * @private
      */
     _onInput: function () {
+        this.isDirty = true;
         this._doDebouncedAction();
     },
     /**