[Merge to M51] ServiceWorker: Remove a bad IPC message check on postMessage()

[Merge to M51] ServiceWorker: Remove a bad IPC message check on postMessage()

This CL removes a bad IPC message check to confirm existence of the sender
provder host on postMessage() because the provider host may be destroyed before
this point when destruction of the provider overtakes postMessage() during
thread hopping on WebServiceWorkerImpl::postMessage().

BUG=608464
Review-Url: https://codereview.chromium.org/1977473003
Cr-Commit-Position: refs/heads/master@{#393495}
(cherry picked from commit 66525f41fc6509604c61a8c0304141662cbdbe97)

Committed: https://chromium.googlesource.com/chromium/src/+/78c0da6b53aaf59d968f8eea8df5fdbff1cd0645

[nhiroki, 2016-05-17 01:35:06]

Description was changed from

==========
[Merge to M51] ServiceWorker: Remove a bad IPC message check on postMessage()

This CL removes a bad IPC message check to confirm existence of the sender
provder host on postMessage() because the provider host may be destroyed before
this point when destruction of the provider overtakes postMessage() during
thread hopping on WebServiceWorkerImpl::postMessage().

BUG=608464

Review-Url: https://codereview.chromium.org/1977473003
Cr-Commit-Position: refs/heads/master@{#393495}
(cherry picked from commit 66525f41fc6509604c61a8c0304141662cbdbe97)
==========

to

==========
[Merge to M51] ServiceWorker: Remove a bad IPC message check on postMessage()

This CL removes a bad IPC message check to confirm existence of the sender
provder host on postMessage() because the provider host may be destroyed before
this point when destruction of the provider overtakes postMessage() during
thread hopping on WebServiceWorkerImpl::postMessage().

BUG=608464

Review-Url: https://codereview.chromium.org/1977473003
Cr-Commit-Position: refs/heads/master@{#393495}
(cherry picked from commit 66525f41fc6509604c61a8c0304141662cbdbe97)

Committed:
https://chromium.googlesource.com/chromium/src/+/78c0da6b53aaf59d968f8eea8df5...
==========

[nhiroki, 2016-05-17 01:35:08]

Committed patchset #1 (id:1) manually as
78c0da6b53aaf59d968f8eea8df5fdbff1cd0645.