cc: Fix overwriting of commit completion event in MFBA mode.

cc: Fix overwriting of commit completion event in MFBA mode.

In main frame before activation (MFBA) mode the following sequence was
problematic:
1. Commit
2. BeginMainFrame
3. StartCommitOnImpl with hold_commit_for_activation=1 (second commit)
4. NotifyReadyToActivate (first commit)
5. Activate (first commit)
6. Commit (second commit)

StartCommitOnImpl will overwrite the completion event and associated
flag that's used in the previous frame's activation. The activation
would then signal the second commit's completion event and that commit
would later crash due to accessing a null completion event.

Added a test specifically for this case and also made the existing test
for hold_commit_for_activation more robust.

R=enne@chromium.org
BUG=613007
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review-Url: https://codereview.chromium.org/2000493002
Cr-Commit-Position: refs/heads/master@{#395185}
(cherry picked from commit 2237c9b93be8a4f6c106149f714b4b88856c4549)

Committed: https://chromium.googlesource.com/chromium/src/+/d7054b5f71c1d15886240ffebc503c45f209396b

[sunnyps, 2016-05-23 19:11:33]

Description was changed from

==========
cc: Fix overwriting of commit completion event in MFBA mode.

In main frame before activation (MFBA) mode the following sequence was
problematic:
1. Commit
2. BeginMainFrame
3. StartCommitOnImpl with hold_commit_for_activation=1 (second commit)
4. NotifyReadyToActivate (first commit)
5. Activate (first commit)
6. Commit (second commit)

StartCommitOnImpl will overwrite the completion event and associated
flag that's used in the previous frame's activation. The activation
would then signal the second commit's completion event and that commit
would later crash due to accessing a null completion event.

Added a test specifically for this case and also made the existing test
for hold_commit_for_activation more robust.

R=enne@chromium.org
BUG=613007
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review-Url: https://codereview.chromium.org/2000493002
Cr-Commit-Position: refs/heads/master@{#395185}
(cherry picked from commit 2237c9b93be8a4f6c106149f714b4b88856c4549)
==========

to

==========
cc: Fix overwriting of commit completion event in MFBA mode.

In main frame before activation (MFBA) mode the following sequence was
problematic:
1. Commit
2. BeginMainFrame
3. StartCommitOnImpl with hold_commit_for_activation=1 (second commit)
4. NotifyReadyToActivate (first commit)
5. Activate (first commit)
6. Commit (second commit)

StartCommitOnImpl will overwrite the completion event and associated
flag that's used in the previous frame's activation. The activation
would then signal the second commit's completion event and that commit
would later crash due to accessing a null completion event.

Added a test specifically for this case and also made the existing test
for hold_commit_for_activation more robust.

R=enne@chromium.org
BUG=613007
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review-Url: https://codereview.chromium.org/2000493002
Cr-Commit-Position: refs/heads/master@{#395185}
(cherry picked from commit 2237c9b93be8a4f6c106149f714b4b88856c4549)

Committed:
https://chromium.googlesource.com/chromium/src/+/d7054b5f71c1d15886240ffebc50...
==========

[sunnyps, 2016-05-23 19:11:35]

Committed patchset #1 (id:1) manually as
d7054b5f71c1d15886240ffebc503c45f209396b (tree was closed).