base: Remove DiscardableMemory::CreateLockedMemory.

base: Remove DiscardableMemory::CreateLockedMemory.

Use DiscardableMemoryAllocator interface directly instead.

This also updates the comments for the DiscardableMemory class
to reflect the current state of discardable memory.

BUG=422953
Committed: https://crrev.com/e7b4233be5698604ef4466d2f76dfd84bfb96542
Cr-Commit-Position: refs/heads/master@{#321076}

[reveman, 2015-03-18 01:10:50]

reveman@chromium.org changed reviewers:
+ avi@chromium.org, thakis@chromium.org

[Nico, 2015-03-18 01:14:09]

lgtm

[Avi (use Gerrit), 2015-03-18 02:18:16]

lgtm

[reveman, 2015-03-18 02:40:42]

The CQ bit was checked by reveman@chromium.org

[reveman, 2015-03-18 02:40:42]

The patchset sent to the CQ was uploaded after l-g-t-m from avi@chromium.org,
thakis@chromium.org
Link to the patchset: https://codereview.chromium.org/1013373002/#ps40001
(title: "fix win build issue")

[commit-bot: I haz the power, 2015-03-18 02:40:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1013373002/40001

[commit-bot: I haz the power, 2015-03-18 04:40:25]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-03-18 04:41:31]

Patchset 3 (id:??) landed as
https://crrev.com/e7b4233be5698604ef4466d2f76dfd84bfb96542
Cr-Commit-Position: refs/heads/master@{#321076}