Print Preview: Improving accessibility of margins UI.

chrome/browser/resources/print_preview/margin_settings.js

Index: chrome/browser/resources/print_preview/margin_settings.js
diff --git a/chrome/browser/resources/print_preview/margin_settings.js b/chrome/browser/resources/print_preview/margin_settings.js
index 819d79fc0ede01d2eef1fc6b049990a3c7752efe..15a6603ea1ebda725a4a4a080b82bd3caafa4a07 100644
--- a/chrome/browser/resources/print_preview/margin_settings.js
+++ b/chrome/browser/resources/print_preview/margin_settings.js
@@ -267,7 +267,7 @@ cr.define('print_preview', function() {
      */
     onSidebarMouseOver_: function(e) {
       if (!this.forceDisplayingMarginLines_)
-        this.marginsUI.hide();
+        this.marginsUI.hide(false);
     },
 
     /**
@@ -298,7 +298,7 @@ cr.define('print_preview', function() {
     onPDFGenerationError_: function() {
       if (this.isCustomMarginsSelected()) {
         this.removeCustomMarginEventListeners_();
-        this.marginsUI.hide();
+        this.marginsUI.hide(true);
       }
     },
 
@@ -426,6 +426,8 @@ cr.define('print_preview', function() {
       $('sidebar').onmouseover = this.onSidebarMouseOver_.bind(this);
       this.eventTracker_.add(
           this.marginsUI, 'DragEvent', this.onDragEvent_.bind(this), false);
+      this.eventTracker_.add(document, 'marginTextboxFocused',
+                             this.onMarginTextboxFocused_.bind(this), false);
     },
 
     /**
@@ -436,7 +438,8 @@ cr.define('print_preview', function() {
       $('mainview').onmouseover = null;
       $('sidebar').onmouseover = null;
       this.eventTracker_.remove(this.marginsUI, 'DragEvent');
-      this.marginsUI.hide();
+      this.eventTracker_.remove(document, 'marginTextboxFocused');
+      this.marginsUI.hide(true);
     },
 
     /**
@@ -470,6 +473,16 @@ cr.define('print_preview', function() {
     },
 
     /**
+     * Executes when a margin textbox is focused. Used for improved
+     * accessibility.
+     * @private
+     */
+    onMarginTextboxFocused_: function() {
+      this.forceDisplayingMarginLines_ = true;
+      this.marginsUI.show();
+    },
+
+    /**
      * Executes when user selects a different margin option, ie,
      * |this.marginList_.selectedIndex| is changed.
      * @private