SPDY4: SpdySession should send SETTINGS acknowledgements.

SPDY4: SpdySession should send SETTINGS acknowledgements.

Queued immediately after an OnSettings() visitor call.

Use a placeholder frame as needed in impacted tests,
so that test flow isn't protocol-version dependent.

BUG=345769
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=270807

[Ryan Hamilton, 2014-05-15 17:47:00]

lgtm

[Johnny, 2014-05-15 18:13:27]

The CQ bit was checked by jgraettinger@chromium.org

[commit-bot: I haz the power, 2014-05-15 18:17:19]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jgraettinger@chromium.org/289823002/1

[commit-bot: I haz the power, 2014-05-15 19:21:33]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)

[commit-bot: I haz the power, 2014-05-15 20:45:24]

Change committed as 270807