Fix 'impl/memory' context key.

Fix 'impl/memory' context key.

Currently the Context is using "1" as the key for the current
transaction. Make it (a) something internal, and (b) a string pointer
for easier Context readability.

BUG=None
TEST=None
R=iannucci@chromium.org

Committed: https://github.com/luci/gae/commit/da301ac8ccee61d3d59e0c548b890f7dd8adfa10

[iannucci, 2016-11-11 20:38:16]

The CQ bit was checked by iannucci@chromium.org

[iannucci, 2016-11-11 20:38:17]

lgtm

[commit-bot: I haz the power, 2016-11-11 20:38:26]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-11-11 20:47:36]

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

[commit-bot: I haz the power, 2016-11-11 20:47:37]

Try jobs failed on following builders:
  Luci-GAE Linux Trusty 64 Tester on luci.infra.try (JOB_FAILED,
https://luci-milo.appspot.com/swarming/task/326df45b8a617710)

[dnj, 2016-11-11 20:49:36]

The CQ bit was checked by dnj@chromium.org

[commit-bot: I haz the power, 2016-11-11 20:49:46]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-11-11 20:53:41]

Description was changed from

==========
Fix 'impl/memory' context key.

Currently the Context is using "1" as the key for the current
transaction. Make it (a) something internal, and (b) a string pointer
for easier Context readability.

BUG=None
TEST=None
R=iannucci@chromium.org
==========

to

==========
Fix 'impl/memory' context key.

Currently the Context is using "1" as the key for the current
transaction. Make it (a) something internal, and (b) a string pointer
for easier Context readability.

BUG=None
TEST=None
R=iannucci@chromium.org

Committed:
https://github.com/luci/gae/commit/da301ac8ccee61d3d59e0c548b890f7dd8adfa10
==========

[commit-bot: I haz the power, 2016-11-11 20:53:42]

Committed patchset #1 (id:1) as
https://github.com/luci/gae/commit/da301ac8ccee61d3d59e0c548b890f7dd8adfa10