add some methods for browser

Change-Id: I0eb787a3ca13a026af8235b06938068d6f15d7d6
not destroy miui home when "always-finish" switch on

N/A

Change-Id: I07e5de24d98184f6e14ff2cab29516529036a1f2
Ref-Id: Iaeda8ec06d76b019fba6f2d58617943af7ca1d75
pick code from android 4.2, fix media scanner slow issue

MIUI-14439

Change-Id: Ia1a2d381e2ab8f614c752db62ad92d4bc0ff5773
Ref-Id: I67a008073070dfb48c3fb5d3a522dfd00a5c3a3c