Move accessibility extension translations to grd file.

ui/accessibility/extensions/highcontrast/manifest.json

 {
-  "name": "High Contrast",
+  "name": "__MSG_appName__",
   "version": "0.6",
-  "description": "Change or invert the color scheme to make webpages easier to read.",
+  "description": "__MSG_appDesc__",
   "manifest_version": 2,
   "permissions": [
     "<all_urls>",
     "tabs"
   ],
   "background": {
     "scripts": [
       "common.js",
       "background.js"
     ]
   },
   "browser_action": {
     "default_icon": "highcontrast-19.png",
-    "default_title": "High Contrast (Shift+F11)",
+    "default_title": "__MSG_appName__",
     "default_popup": "popup.html"
   },
   "content_scripts": [
     {
       "run_at": "document_start",
       "matches": [
         "<all_urls>"
       ],
       "all_frames": true,
       "css": [
         "highcontrast.css"
       ],
       "js": [
         "highcontrast.js"
       ]
     }
   ],
   "icons": {
     "16": "highcontrast-16.png",
     "48": "highcontrast-48.png",
     "128": "highcontrast-128.png"
   }
 }