Android denial of service attack using class 0 SMS messages

Bug 9702645
Bug 11970403 - Change to ClassZeroActivity to singleTask

Cherry pick the change from master.

Making every AlertDialog immediately visible can lead to exhaustion
of graphics-related resources, typically memory, resulting in a
broken bufferqueue/hw renderer, and subsequent system crash.

Make ClassZeroActivity a singleTask activity, and queue incoming
messages if one is already being displayed.

Change-Id: I0aef7b857364acc404e79581ba5e503571065483
Import translations. DO NOT MERGE

Change-Id: Id82f32c4e67b791c497dac8a5366e83a3c3befee
Auto-generated-cl: translation import
Import translations. DO NOT MERGE

Change-Id: Ib81400a83d3319e1a69a620ac64dba04a0324aaf
Auto-generated-cl: translation import
Import translations. DO NOT MERGE

Change-Id: I3ad993c5a135428dc543d30bc08eb9139127bf6e
Auto-generated-cl: translation import
Import translations. DO NOT MERGE

Change-Id: Ib50c04b62425bf3cc09512ef63c28430ddd0706b
Auto-generated-cl: translation import
Merge remote-tracking branch 'remotes/aosp/kitkat-mr2-release' into kk44