Fix the problem that releasing a key after pressing multiple modifiers corrupts keyboard overlay

chrome/browser/resources/keyboard_overlay.js

Index: chrome/browser/resources/keyboard_overlay.js
diff --git a/chrome/browser/resources/keyboard_overlay.js b/chrome/browser/resources/keyboard_overlay.js
index 1d19496c1629e4dac6936966320b080262c9ddcd..554797af86c8278ae5a7b2562814528c9f301349 100644
--- a/chrome/browser/resources/keyboard_overlay.js
+++ b/chrome/browser/resources/keyboard_overlay.js
@@ -120,15 +120,24 @@ function getModifiers(e) {
   if (!e) {
     return [];
   }
+  var isKeyDown = (e.type == 'keydown');
+  var modifierToKeyCode = {'SHIFT': 16, 'CTRL': 17, 'ALT': 18};
   var modifiers = [];

[mazda, 2011/04/18 11:00:20]

Please move the declaration right before line 137.

-  if (e.keyCode == 16 || e.shiftKey) {
-    modifiers.push('SHIFT');
-  }
-  if (e.keyCode == 17 || e.ctrlKey) {
-    modifiers.push('CTRL');
+  var modifier;

[mazda, 2011/04/18 11:00:20]

How about moving modifier to for-loop?

for (var modifier in modifierToKeyCode) {
..

for (var modifier in pressed) {
...

+  var pressed = {'SHIFT': e.shiftKey, 'CTRL': e.ctrlKey, 'ALT': e.altKey};
+  // if e.keyCode is one of Shift, Ctrl and Alt, pressed should
+  // be changed because the key currently pressed
+  // does not affect the values of e.shiftKey, e.ctrlKey and e.altKey
+  for (modifier in modifierToKeyCode) {
+    if (e.keyCode == modifierToKeyCode[modifier]) {
+      pressed[modifier] = isKeyDown;
+    }
   }
-  if (e.keyCode == 18 || e.altKey) {
-    modifiers.push('ALT');
+  // make the result array
+  for (modifier in pressed) {
+    if (pressed[modifier]) {
+      modifiers.push(modifier);
+    }
   }
   return modifiers.sort();
 }
@@ -265,8 +274,7 @@ function getKeyTextValue(keyData) {
 /**
  * Updates the whole keyboard.
  */
-function update(e) {
-  var modifiers = getModifiers(e);
+function update(modifiers) {
   var instructions = document.getElementById('instructions');
   if (modifiers.length == 0) {
     instructions.style.visibility = 'visible';
@@ -325,20 +333,22 @@ function update(e) {
  * A callback furnction for the onkeydown event.
  */
 function keydown(e) {
+  var modifiers = getModifiers(e);
   if (!getKeyboardOverlayId()) {
     return;
   }
-  update(e);
+  update(modifiers);
 }
 
 /**
  * A callback furnction for the onkeyup event.
  */
 function keyup(e) {

[mazda, 2011/04/18 11:00:20]

How about merging this function into keydown?

+  var modifiers = getModifiers(e);
   if (!getKeyboardOverlayId()) {
     return;
   }
-  update();
+  update(modifiers);
 }
 
 /**