Adding `content_security_policy` to imageinfo extension.

chrome/common/extensions/docs/samples.json

 {
   "api": {
     "chrome.bookmarks.create": "bookmarks.html#method-create",
     "chrome.bookmarks.export": "bookmarks.html#method-export",
     "chrome.bookmarks.get": "bookmarks.html#method-get",
     "chrome.bookmarks.getChildren": "bookmarks.html#method-getChildren",
     "chrome.bookmarks.getRecent": "bookmarks.html#method-getRecent",
     "chrome.bookmarks.getSubTree": "bookmarks.html#method-getSubTree",
     "chrome.bookmarks.getTree": "bookmarks.html#method-getTree",
     "chrome.bookmarks.import": "bookmarks.html#method-import",
@@ skipping 1259 matching lines @@
       "name": "Imageinfo",
       "packaged_app": false,
       "path": "examples\/extensions\/imageinfo\/",
       "protocols": [
         "http:\/\/",
         "https:\/\/"
       ],
       "search_string": "IMAGEINFO GET IMAGE INFO FOR IMAGES, INCLUDING EXIF DATA BACKGROUND_PAGE CONTEXTMENUS TABS CHROME.CONTEXTMENUS.CREATE CHROME.TABS.GET CHROME.TABS.GETCURRENT CHROME.WINDOWS.CREATE CHROME.WINDOWS.UPDATE",
       "source_files": [
         "background.html",
+        "background.js",
         "imageinfo\/binaryajax.js",
         "imageinfo\/exif.js",
         "imageinfo\/imageinfo.js",
+        "info.css",
         "info.html",
+        "info.js",
         "manifest.json"
       ],
-      "source_hash": "c746d9114348f4b414c1ec05e988e2807feb963a",
+      "source_hash": "3a61d1ad772ef01e0d3cc01a8bedbe7da452dd0b",
       "zip_path": "examples\/extensions\/imageinfo.zip"
     },
     {
       "api_calls": [
         "chrome.browserAction.onClicked",
         "chrome.browserAction.setIcon",
         "chrome.browserAction.setTitle",
         "chrome.experimental.debugger.attach",
         "chrome.experimental.debugger.detach",
         "chrome.experimental.debugger.onDetach",
@@ skipping 1035 matching lines @@
       "source_files": [
         "manifest.json",
         "popup.html",
         "sample.css"
       ],
       "source_hash": "c8bfc2b60f25c24dc3c5aaf75dd635c9419df66d",
       "zip_path": "examples\/api\/extension\/isAllowedAccess.zip"
     }
   ]
 }