Fix race condition with multiplexed message pipes.

Fix race condition with multiplexed message pipes.

The problem was that if a MessagePipeDispatcher was connected to a RoutedRawChannel that had buffered messages to it. OnReadMessage would be called first which would tell the awakables that it's ready for read.  But if the awakable called ReadMessage before GotNonTransferableChannel was called, then they wouldn't get any messages because channel_ was null.

BUG=561803
TEST=out/Debug/mojo_runner mojo:example_main --use-mus-in-renderer http://www.slashdot.org and then ctrl+n works

Committed: https://crrev.com/cba3547586790f12aa2cec55f140c87f7aca0c06
Cr-Commit-Position: refs/heads/master@{#365395}

[jam, 2015-12-15 21:38:55]

jam@chromium.org changed reviewers:
+ yzshen@chromium.org

[jam, 2015-12-15 21:54:26]

Description was changed from

==========
Fix race condition with multiplexed message pipes.

The problem was that if a MessagePipeDispatcher was connected to a
RoutedRawChannel that had buffered messages to it. OnReadMessage would be called
first which would tell the awakables that it's ready for read.  But if the
awakable called ReadMessage before GotNonTransferableChannel was called, then
they wouldn't get any messages because channel_ was null.

BUG=561803
==========

to

==========
Fix race condition with multiplexed message pipes.

The problem was that if a MessagePipeDispatcher was connected to a
RoutedRawChannel that had buffered messages to it. OnReadMessage would be called
first which would tell the awakables that it's ready for read.  But if the
awakable called ReadMessage before GotNonTransferableChannel was called, then
they wouldn't get any messages because channel_ was null.

BUG=561803
TEST=out/Debug/mojo_runner mojo:example_main --use-mus-in-renderer
http://www.slashdot.org and then ctrl+n works
==========

[yzshen1, 2015-12-15 22:05:48]

lgtm

[jam, 2015-12-15 22:57:18]

The CQ bit was checked by jam@chromium.org

[commit-bot: I haz the power, 2015-12-15 23:00:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1524333002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1524333002/1

[commit-bot: I haz the power, 2015-12-15 23:44:46]

Description was changed from

==========
Fix race condition with multiplexed message pipes.

The problem was that if a MessagePipeDispatcher was connected to a
RoutedRawChannel that had buffered messages to it. OnReadMessage would be called
first which would tell the awakables that it's ready for read.  But if the
awakable called ReadMessage before GotNonTransferableChannel was called, then
they wouldn't get any messages because channel_ was null.

BUG=561803
TEST=out/Debug/mojo_runner mojo:example_main --use-mus-in-renderer
http://www.slashdot.org and then ctrl+n works
==========

to

==========
Fix race condition with multiplexed message pipes.

The problem was that if a MessagePipeDispatcher was connected to a
RoutedRawChannel that had buffered messages to it. OnReadMessage would be called
first which would tell the awakables that it's ready for read.  But if the
awakable called ReadMessage before GotNonTransferableChannel was called, then
they wouldn't get any messages because channel_ was null.

BUG=561803
TEST=out/Debug/mojo_runner mojo:example_main --use-mus-in-renderer
http://www.slashdot.org and then ctrl+n works
==========

[commit-bot: I haz the power, 2015-12-15 23:44:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-12-15 23:45:54]

Description was changed from

==========
Fix race condition with multiplexed message pipes.

The problem was that if a MessagePipeDispatcher was connected to a
RoutedRawChannel that had buffered messages to it. OnReadMessage would be called
first which would tell the awakables that it's ready for read.  But if the
awakable called ReadMessage before GotNonTransferableChannel was called, then
they wouldn't get any messages because channel_ was null.

BUG=561803
TEST=out/Debug/mojo_runner mojo:example_main --use-mus-in-renderer
http://www.slashdot.org and then ctrl+n works
==========

to

==========
Fix race condition with multiplexed message pipes.

The problem was that if a MessagePipeDispatcher was connected to a
RoutedRawChannel that had buffered messages to it. OnReadMessage would be called
first which would tell the awakables that it's ready for read.  But if the
awakable called ReadMessage before GotNonTransferableChannel was called, then
they wouldn't get any messages because channel_ was null.

BUG=561803
TEST=out/Debug/mojo_runner mojo:example_main --use-mus-in-renderer
http://www.slashdot.org and then ctrl+n works

Committed: https://crrev.com/cba3547586790f12aa2cec55f140c87f7aca0c06
Cr-Commit-Position: refs/heads/master@{#365395}
==========

[commit-bot: I haz the power, 2015-12-15 23:45:55]

Patchset 1 (id:??) landed as
https://crrev.com/cba3547586790f12aa2cec55f140c87f7aca0c06
Cr-Commit-Position: refs/heads/master@{#365395}