adb_gdb : Import tools/gdb/gdb_chrome.py as part of adb_gdb script

Import tools/gdb/gdb_chrome.py as part of adb_gdb script

Presently, first time developer need to copy paste source for inserting gdb_chrome.py in ~/.gdbinit file.

This change avoids the manual step & works seem less for first time developer also. 

BUG=None

Committed: https://crrev.com/145425d17c8351595048b0dff319e8ff284d983f
Cr-Commit-Position: refs/heads/master@{#291581}

[kishorags_, 2014-08-05 12:29:10]

PTAL. Thanks

[RaviKasibhatla, 2014-08-07 07:36:56]

lgtm

non-owner lgtm. :)

[kishorags_, 2014-08-17 10:15:11]

The CQ bit was checked by kishor.ag@samsung.com

[commit-bot: I haz the power, 2014-08-17 10:15:50]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kishor.ag@samsung.com/444593003/1

[commit-bot: I haz the power, 2014-08-17 11:27:52]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  mac_gpu_retina_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu_retina_tr...)
  ios_rel_device_ninja on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)

[commit-bot: I haz the power, 2014-08-17 12:00:06]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-08-17 12:00:08]

Try jobs failed on following builders:
  mac_gpu_retina_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu_retina_tr...)

[kishorags_, 2014-08-23 10:54:25]

The CQ bit was checked by kishor.ag@samsung.com

[commit-bot: I haz the power, 2014-08-23 10:55:57]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kishor.ag@samsung.com/444593003/1

[commit-bot: I haz the power, 2014-08-23 21:27:31]

Committed patchset #1 (1) as ed81d04f55f389ebaa792e974e60ad32407734e0

[commit-bot: I haz the power, 2014-09-10 02:30:56]

Patchset 1 (id:??) landed as
https://crrev.com/145425d17c8351595048b0dff319e8ff284d983f
Cr-Commit-Position: refs/heads/master@{#291581}