Add color enhancer as a chromium accessibility extensions.

ui/accessibility/extensions/colorenhancer/src/common.js

Index: ui/accessibility/extensions/colorenhancer/src/common.js
diff --git a/ui/accessibility/extensions/colorenhancer/src/common.js b/ui/accessibility/extensions/colorenhancer/src/common.js
new file mode 100644
index 0000000000000000000000000000000000000000..d0b6f5eef410c4f90240ef7b84cc4b82c89e1fc2
--- /dev/null
+++ b/ui/accessibility/extensions/colorenhancer/src/common.js
@@ -0,0 +1,241 @@
+// Copyright 2015 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.
+
+// TODO(wnwen): Move most of these functions to their own page rather than
+//     common, which should be shared with content script.
+
+// TODO(wnwen): Revamp storage, move to chrome.storage.local, wrap calls, and
+//     add JsDocs.
+
+/**
+ * TODO(wnwen): Remove this and use actual web API.
+ */
+function $(id) {
+  return document.getElementById(id);
+}
+
+
+/**
+ * TODO(wnwen): Remove this, it's terrible.
+ */
+function siteFromUrl(url) {
+  var a = document.createElement('a');
+  a.href = url;
+  return a.hostname;
+}
+
+/**
+ * The filter should not apply to these URLs.

[kevers, 2015/03/10 14:07:51]

@param

[Peter Wen, 2015/03/10 19:00:55]

Done.

+ */
+function isDisallowedUrl(url) {
+  return url.indexOf('chrome') == 0 || url.indexOf('about') == 0;
+}
+
+
+var DEFAULT_DELTA = 1.0;
+var LOCAL_STORAGE_TAG_DELTA = 'cvd_delta';
+var LOCAL_STORAGE_TAG_SITE_DELTA = 'cvd_site_deltas';
+
+
+function validDelta(delta) {
+  return delta >= 0 && delta <= 1;

[kevers, 2015/03/10 14:07:51]

This method looks overly specialized.  OK with fixing in a followup CL.  We
could achieve the same effect below with a generic clamp(min,max,default)
method.  It could then be used for validating any numeric value.

[Peter Wen, 2015/03/10 19:00:55]

Acknowledged.

+}
+
+
+function getDefaultDelta() {
+  var delta = localStorage[LOCAL_STORAGE_TAG_DELTA];
+  if (validDelta(delta)) {
+    return delta;
+  }
+  delta = DEFAULT_DELTA;
+  localStorage[LOCAL_STORAGE_TAG_DELTA] = delta;
+  return delta;
+}
+
+
+function setDefaultDelta(delta) {
+  if (!validDelta(delta)) {
+    delta = DEFAULT_DELTA;
+  }
+  localStorage[LOCAL_STORAGE_TAG_DELTA] = delta;
+}
+
+
+function getSiteDelta(site) {
+  var delta = getDefaultDelta();
+  try {
+    var siteDeltas = JSON.parse(localStorage[LOCAL_STORAGE_TAG_SITE_DELTA]);
+    delta = siteDeltas[site];
+    if (!validDelta(delta)) {
+      delta = getDefaultDelta();
+    }
+  } catch (e) {
+    delta = getDefaultDelta();
+  }
+  return delta;
+}
+
+
+function setSiteDelta(site, delta) {
+  if (!validDelta(delta)) {
+    delta = getDefaultDelta();
+  }
+  var siteDeltas = {};
+  try {
+    siteDeltas = JSON.parse(localStorage[LOCAL_STORAGE_TAG_SITE_DELTA]);
+  } catch (e) {
+    siteDeltas = {};
+  }
+  siteDeltas[site] = delta;
+  localStorage[LOCAL_STORAGE_TAG_SITE_DELTA] = JSON.stringify(siteDeltas);
+}
+
+
+function resetSiteDeltas() {
+  var siteDeltas = {};
+  localStorage[LOCAL_STORAGE_TAG_SITE_DELTA] = JSON.stringify(siteDeltas);
+}
+
+
+// ======= Severity setting =======
+
+var DEFAULT_SEVERITY = 1.0;
+var LOCAL_STORAGE_TAG_SEVERITY = 'cvd_severity';
+var LOCAL_STORAGE_TAG_SITE_SEVERITY = 'cvd_severities';
+
+
+function validSeverity(severity) {

[kevers, 2015/03/10 14:07:51]

See note above for validDelta.

[Peter Wen, 2015/03/10 19:00:55]

Agreed, quite a bit of this storage code can be DRY'ed. :)

+  return severity >= 0 && severity <= 1;
+}
+
+
+function getDefaultSeverity() {
+  var severity = localStorage[LOCAL_STORAGE_TAG_SEVERITY];
+  if (validSeverity(severity)) {
+    return severity;
+  }
+  severity = DEFAULT_SEVERITY;
+  localStorage[LOCAL_STORAGE_TAG_SEVERITY] = severity;
+  return severity;
+}
+
+
+function setDefaultSeverity(severity) {
+  if (!validSeverity(severity)) {
+    severity = DEFAULT_SEVERITY;
+  }
+  localStorage[LOCAL_STORAGE_TAG_SEVERITY] = severity;
+}
+
+
+// TODO(mustaq): Remove site-specific severity setting.
+function getSiteSeverity(site) {
+  var severity = getDefaultSeverity();
+  try {
+    var siteSeverities =
+        JSON.parse(localStorage[LOCAL_STORAGE_TAG_SITE_SEVERITY]);
+    severity = siteSeverities[site];
+    if (!validSeverity(severity)) {
+      severity = getDefaultSeverity();
+    }
+  } catch (e) {
+    severity = getDefaultSeverity();
+  }
+  return severity;
+}
+
+
+function setSiteSeverity(site, severity) {
+  if (!validSeverity(severity)) {
+    severity = getDefaultSeverity();
+  }
+  var siteSeverities = {};
+  try {
+    siteSeverities = JSON.parse(localStorage[LOCAL_STORAGE_TAG_SITE_SEVERITY]);
+  } catch (e) {
+    siteSeverities = {};
+  }
+  siteSeverities[site] = severity;
+  localStorage[LOCAL_STORAGE_TAG_SITE_SEVERITY] =
+      JSON.stringify(siteSeverities);
+}
+
+
+function resetSiteSeverities() {
+  var siteSeverities = {};
+  localStorage[LOCAL_STORAGE_TAG_SITE_SEVERITY] =
+      JSON.stringify(siteSeverities);
+}
+
+
+// ======= Type setting =======
+
+var DEFAULT_TYPE = 'PROTANOMALY';

[kevers, 2015/03/10 14:07:51]

Less error prone to use an enumeration. i.e.:

/**
 * @enum {string}
 */
 var CvdType = {
    PROTANOMALY, 'PROTANOMALY'
    ...
 };

This way we get a javascript error if there is a typo in the name rather than
hitting an unexpected conditional. the method validType then becomes

validType(type) {
  return type in CvdType;
}

Naturally, we would want a shared enum across js files.  This change can be in a
followup CL.

[Peter Wen, 2015/03/10 19:00:55]

Agreed. Added TODO.

In Chrome 42 we can do
var otherEnum = {
  [CvdType.PROTANOMALY]: data,
}

https://www.chromestatus.com/feature/4873630588600320

+var LOCAL_STORAGE_TAG_TYPE = 'cvd_type';
+
+
+function validType(type) {
+  return type === 'PROTANOMALY' ||
+      type === 'DEUTERANOMALY' ||
+      type === 'TRITANOMALY';
+}
+
+
+function getDefaultType() {
+  var type = localStorage[LOCAL_STORAGE_TAG_TYPE];
+  if (validType(type)) {
+    return type;
+  }
+  type = DEFAULT_TYPE;
+  localStorage[LOCAL_STORAGE_TAG_TYPE] = type;
+  return type;
+}
+
+
+function setDefaultType(type) {
+  if (!validType(type)) {
+    type = DEFAULT_TYPE;
+  }
+  localStorage[LOCAL_STORAGE_TAG_TYPE] = type;
+}
+
+
+// ======= Simulate setting =======
+
+var DEFAULT_SIMULATE = false;
+var LOCAL_STORAGE_TAG_SIMULATE = 'cvd_simulate';
+
+
+function validSimulate(simulate) {
+  return simulate == true || simulate == false;
+}
+
+
+function getDefaultSimulate() {
+  var simulate = localStorage[LOCAL_STORAGE_TAG_SIMULATE];
+
+  //Make it a boolean if possible
+  if (simulate === 'true') {
+    simulate = true;
+  } else if (simulate === 'false') {
+    simulate = false;
+  } else {
+    simulate = 'undef';
+  }
+
+  if (validSimulate(simulate)) {
+    return simulate;
+  }
+  simulate = DEFAULT_SIMULATE;
+  localStorage[LOCAL_STORAGE_TAG_SIMULATE] = simulate;
+  return simulate;
+}
+
+
+function setDefaultSimulate(simulate) {
+  if (!validSimulate(simulate)) {
+    simulate = DEFAULT_SIMULATE;
+  }
+  localStorage[LOCAL_STORAGE_TAG_SIMULATE] = simulate;
+}