Change the prototype of ChannelIDSource::GetChannelIDKey() to allow an

Change the prototype of ChannelIDSource::GetChannelIDKey() to allow an
asynchronous implementation.

Current ChannelIDSource implementations work in synchronous mode. So
QuicCryptoClientStream still calls ChannelIDSource::GetChannelIDKey() as
a synchronous function. In a future CL, QuicCryptoClientStream will properly
call ChannelIDSource::GetChannelIDKey() as an asynchronous function.

Note that ChannelIDSourceForTesting() returns a ChannelIDSource that works
in synchronous mode.

Merge internal CL: 68399207

R=rch@chromium.org,rtenneti@chromium.org
BUG=none

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=275634

[wtc, 2014-06-06 22:16:49]

Please review.

Ryan: this is the second-to-last CL of the series. You already reviewed the
internal version of this CL.

[Ryan Hamilton, 2014-06-06 22:27:02]

lgtm

[ramant (doing other things), 2014-06-06 22:39:04]

On 2014/06/06 22:27:02, Ryan Hamilton wrote:
> lgtm

+1. Thanks for doing this.

[wtc, 2014-06-06 22:44:03]

The CQ bit was checked by wtc@chromium.org

[commit-bot: I haz the power, 2014-06-06 22:44:50]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/wtc@chromium.org/320663002/20001

[commit-bot: I haz the power, 2014-06-07 02:51:52]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_x64_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_x64_rel/...)

[commit-bot: I haz the power, 2014-06-07 06:31:29]

Change committed as 275634