WebUI: For cr-dialog, make Enter click the action-button, if it exists.

ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js

Index: ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js
diff --git a/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js b/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js
index d15ed9b8173a769d12afe886806d1509a99cfffc..9a1332ff14038c4fd380741a46b9762dfcab95ee 100644
--- a/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js
+++ b/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js
@@ -29,6 +29,14 @@ Polymer({
       type: Boolean,
       value: false,
     },
+
+    /**
+     * True if the dialog should ignore 'Enter' keypresses.
+     */
+    ignoreEnterKey: {
+      type: Boolean,
+      value: false,
+    },
   },
 
   /** @override */
@@ -39,6 +47,9 @@ Polymer({
       if (!this.ignorePopstate && this.open)
         this.cancel();
     }.bind(this));
+
+    if (!this.ignoreEnterKey)
+      this.addEventListener('keypress', this.onKeypress_.bind(this));
   },
 
   cancel: function() {
@@ -58,4 +69,21 @@ Polymer({
   getCloseButton: function() {
     return this.$.close;
   },
+
+  /**
+   * @param {!KeyboardEvent} e
+   * @private
+   */
+  onKeypress_: function(e) {
+    if (e.target != this)

[tommycli, 2017/03/31 00:16:55]

This is more conservative than the Options equivalent code [1], but I suggest we
roll with this for now, and amp-up the aggression later.

We will probably have to amp up the aggression to eliminate all these redundant
handlers [2] already within Settings, but I think we should save that for a
followup CL if you like this one.

[1] 
https://cs.chromium.org/chromium/src/ui/webui/resources/js/cr/ui/overlay.js?t...
[2]
https://cs.chromium.org/search/?q=onKeypress+file:%5Esrc/chrome/browser/resou...

+      return;
+    if (e.key != 'Enter')
+      return;
+
+    var actionButton = this.querySelector('.action-button');

[dpapad, 2017/03/31 02:08:29]

Should we add an assertion() for this, instead of silently doing nothing? Do we
have dialogs that don't have an action button, in Settings or some other WebUI
page?

[tommycli, 2017/04/03 16:53:34]

Hey demetrios, here's an example where there's no action-button:

https://cs.chromium.org/chromium/src/chrome/browser/resources/settings/blueto...

In any case, I don't think we should assert, since it's not in the contract for
a cr-dialog that it -must- have a button with the action-button class.

+    if (actionButton && !actionButton.disabled) {

[dpapad, 2017/03/31 02:08:29]

Do we need to check for |disabled| at all? I believe that click() is a no-op if
the element is disabled.

It would be nice if we can keep the dialog oblivious to the state of the action
button. At least until (if ever) we decide to address the multiple redundant
handlers you linked above.

[tommycli, 2017/04/03 16:53:34]

Hi, disabled buttons can still be 'click()' ed. See example:
https://jsfiddle.net/4rdzc3tf/1/

[dpapad, 2017/04/03 18:20:07]

Ok. I recall having problems "clicking" disabled buttons in the past. Maybe I am
thinking of MockInteractions.tap(), not sure.

+      actionButton.click();
+      e.preventDefault();
+    }
+  },
 });