add some methods for browser

Change-Id: Ib29061129151cb08a244d430aa55b7d5ba622aa0
not destroy miui home when "always-finish" switch on

N/A

Change-Id: Ie2faee8044c188555aa1192445c9072822c5bccd
Ref-Id: Iaeda8ec06d76b019fba6f2d58617943af7ca1d75
pick code from android 4.2, fix media scanner slow issue

MIUI-14439

Change-Id: I08e0c8db3dc7c4628eb1fef2ad4c5e35a14d7ccb
Ref-Id: I67a008073070dfb48c3fb5d3a522dfd00a5c3a3c