Fix shared_memory_posix Map()

mmap returns -1 on failure and in the posix implementation of SharedMemory, this was setting memory_ to -1. However the interface for SharedMemory specifies that memory_ should be NULL if it is unmapped.

Furthermore there was  DCHECK included to check the success of mmap, but I feel this is incorrect because we are returning the success (e.g. other platform implementations don't do this). The caller can DCHECK if they need. We could change this to a LOG call.

BUG=None
TEST=out/Debug/base_unittests


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=133516

[brettw, 2012-04-23 19:24:54]

lgtm

[commit-bot: I haz the power, 2012-04-23 19:31:48]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/raymes@chromium.org/10174007/1

[commit-bot: I haz the power, 2012-04-23 21:00:08]

Change committed as 133516