Pass the kGCCallbackFlagForced from AdjustAmountOfExternalAllocatedMemory.

Pass the kGCCallbackFlagForced flag when invoking Heap::CollectAllGarbage from AdjustAmountOfExternalAllocatedMemory.

This forces the second pass of the pending phantom callbacks to run immediately after the first.

BUG=chromium:511294
LOG=Y

Committed: https://crrev.com/aec8987b5ee55fa46b90b58927e957a4e5f19c09
Cr-Commit-Position: refs/heads/master@{#29933}

[epertoso, 2015-07-28 11:04:58]

epertoso@chromium.org changed reviewers:
+ jochen@chromium.org

[epertoso, 2015-07-28 11:05:09]

The CQ bit was checked by epertoso@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-07-28 11:05:22]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1252993004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1252993004/20001

[jochen (gone - plz use gerrit), 2015-07-28 13:07:09]

lgtm

[commit-bot: I haz the power, 2015-07-30 08:16:05]

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

[commit-bot: I haz the power, 2015-07-30 08:16:05]

Dry run: This issue passed the CQ dry run.

[epertoso, 2015-07-30 13:16:01]

The CQ bit was checked by epertoso@chromium.org

[commit-bot: I haz the power, 2015-07-30 13:16:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1252993004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1252993004/20001

[commit-bot: I haz the power, 2015-07-30 13:41:49]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-30 13:42:10]

Patchset 2 (id:??) landed as
https://crrev.com/aec8987b5ee55fa46b90b58927e957a4e5f19c09
Cr-Commit-Position: refs/heads/master@{#29933}