Squashed commit of the following:

commit 07b4d10f6e5d81e74669a833d5716b55141d4551
Author: ku <kentaro.kumagai@aurorafeint.com>
Date:   Wed Apr 10 02:33:04 2013 -0700

    replace extension.getBackgroundPage() with runtime.getBackgroundPage()

commit 6201d0148a90b67c5364edf4fc4eb2162ec57d53
Merge: 331d8fd e48a30c
Author: KUMAGAI Kentaro <ku0522a@gmail.com>
Date:   Tue Apr 9 09:43:03 2013 -0700

    Merge pull request #4 from hnakamur/chrome_26_and_27

    Chrome 26 and 27

commit e48a30ce4576ea635d34dee6564c059084ca051a
Author: Hiroaki Nakamura <hnakamur@gmail.com>
Date:   Wed Apr 10 01:19:03 2013 +0900

    Change version to 0.1.3.

commit 004338f70f056ed6ad8800defcb629ff3987e752
Author: Hiroaki Nakamura <hnakamur@gmail.com>
Date:   Wed Apr 10 01:18:33 2013 +0900

    Add javascript files to manifest.json.

commit 331d8fd181028d98caa5adf212000776605f6a2c
Merge: 815eba7 c082e7e
Author: KUMAGAI Kentaro <ku0522a@gmail.com>
Date:   Mon Apr 8 21:25:58 2013 -0700

    Merge pull request #3 from hnakamur/migrate_to_manifest_v2

    Migrate to manifest v2

commit c082e7eacc72a240c605b21afdb466d5c6c6005d
Author: Hiroaki Nakamura <hnakamur@gmail.com>
Date:   Tue Apr 9 10:28:08 2013 +0900

    Create external JavaScript files, because inline JavaScripts will not be
    executed in the new Content Security Policy.

commit 3f5f1406dae50aec3cd6ed0e2d7b3b3a735ee7e9
Author: Hiroaki Nakamura <hnakamur@gmail.com>
Date:   Tue Apr 9 10:27:34 2013 +0900

    Change popup to default_popup in browser_action.

commit dd13cf4f2e273decef2da99a768197fceb30d793
Author: Hiroaki Nakamura <hnakamur@gmail.com>
Date:   Tue Apr 9 10:02:57 2013 +0900

    Use sendMessage and onMessage instead of sendRequest and onRequest.

commit c25207cb87df2067f5a5e9e65270af2f3960ecc8
Author: Hiroaki Nakamura <hnakamur@gmail.com>
Date:   Tue Apr 9 09:58:09 2013 +0900

    Use chrome.extension instead of chrome.self which is removed.

commit 8addf62f5099f29fc1c6d1a79983dd4b9a78f246
Author: Hiroaki Nakamura <hnakamur@gmail.com>
Date:   Tue Apr 9 09:57:41 2013 +0900

    Change manifest version to 2.