Add arch support for tombstone.py

Add arch support for tombstone.py

'stack' tool has archtechture support by passing --arch argument, if it
is not given, arm will be used by default. Thus the stack trace will be
wrongly reported.

To resolve it, 'arch' prop is added to tombstone when fetching from
device, and pass it to symbol.ARCH at end.

R=jbudorick@chromium.org
BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285910

[jbudorick, 2014-07-25 14:19:02]

https://codereview.chromium.org/416983004/diff/1/build/android/tombstones.py
File build/android/tombstones.py (right):

https://codereview.chromium.org/416983004/diff/1/build/android/tombstones.py#...
build/android/tombstones.py:56: def _GetDeviceArch(device):
This function isn't needed.

https://codereview.chromium.org/416983004/diff/1/build/android/tombstones.py#...
build/android/tombstones.py:100: include_stack: boolean whether to include stack
data in output.
Please add a description for arch here.

https://codereview.chromium.org/416983004/diff/1/build/android/tombstones.py#...
build/android/tombstones.py:171: 'arch': _GetDeviceArch(device),
  _GetDeviceArch(device)

should be replaced by

  device.GetProp('ro.product.cpu.api')

[haltonhuo, 2014-07-28 02:03:45]

jbudorick, many thanks for your review, all your comments are addressed in patch
set2, pleas review.

[haltonhuo, 2014-07-28 02:03:47]

jbudorick, many thanks for your review, all your comments are addressed in patch
set2, please review.

[jbudorick, 2014-07-28 14:21:04]

lgtm

Thanks for the patch!

[haltonhuo, 2014-07-28 14:23:37]

The CQ bit was checked by halton.huo@intel.com

[commit-bot: I haz the power, 2014-07-28 14:24:23]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/halton.huo@intel.com/416983004/20001

[commit-bot: I haz the power, 2014-07-28 15:35:22]

Change committed as 285910