Using the new webkit CSS change notification instead of a mutation observer.

chrome/test/data/extensions/api_test/declarative_content/overview/background.js

Index: chrome/test/data/extensions/api_test/declarative_content/overview/background.js
diff --git a/chrome/test/data/extensions/api_test/declarative_content/overview/background.js b/chrome/test/data/extensions/api_test/declarative_content/overview/background.js
index a23b54653eec856a030fe9698d1c8a4dd5d33914..663c36ded83da4799dd67ed7b76b2153b617e0a2 100644
--- a/chrome/test/data/extensions/api_test/declarative_content/overview/background.js
+++ b/chrome/test/data/extensions/api_test/declarative_content/overview/background.js
@@ -9,7 +9,9 @@ var ShowPageAction = chrome.declarativeContent.ShowPageAction;
 
 var rule0 = {
   conditions: [new PageStateMatcher({pageUrl: {hostPrefix: "test1"}}),
-               new PageStateMatcher({css: ["input[type='password']"]})],
+               // TODO(jyasskin): Normalize the CSS selector value and switch
+               // this back to single quotes.
+               new PageStateMatcher({css: ["input[type=\"password\"]"]})],
   actions: [new ShowPageAction()]
 }