Refactored the browser tester waiting logic into its own class.
Refactored the browser tester waiting logic into its own class.

This should make writing certain kinds of tests easier.

BUG= none
TEST= ./scons chrome_browser_tests

Review URL: http://codereview.chromium.org/6735072

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@4770 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,nacl-webkit/native_client,nacl-webkit/native_client,sbc100/native_client,nacl-webkit/native_client