Fixing size_t -> int truncation in //net/quic/spdy_utils.cc

Fixing size_t -> int truncation in //net/quic/spdy_utils.cc

Trivial change altering length from int to size_t; since this variable
is initialised from a size_t, and passed as a parameter to two functions
that accept a size_t parameter.

BUG=488553
Committed: https://crrev.com/f2415b13846f8217550257e85d3cb0130ddff197
Cr-Commit-Position: refs/heads/master@{#332370}

[markbrand, 2015-05-26 14:56:11]

markbrand@google.com changed reviewers:
+ eroman@chromium.org

[markbrand, 2015-05-26 15:27:59]

eroman@, figured if you are going to be doing some work on 488553 I'd try and
send patches for obvious, trivial cases that I spot.

[eroman, 2015-05-26 16:42:23]

lgtm

[markbrand, 2015-05-27 09:04:10]

The CQ bit was checked by markbrand@google.com

[markbrand, 2015-05-27 09:04:12]

The CQ bit was unchecked by markbrand@google.com

[markbrand, 2015-06-02 09:27:25]

The CQ bit was checked by markbrand@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-06-02 09:28:03]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1157103002/1

[commit-bot: I haz the power, 2015-06-02 11:35:47]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-02 11:35:48]

Dry run: This issue passed the CQ dry run.

[markbrand, 2015-06-02 11:41:26]

The CQ bit was checked by markbrand@google.com

[commit-bot: I haz the power, 2015-06-02 11:41:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1157103002/1

[commit-bot: I haz the power, 2015-06-02 11:45:02]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-02 11:45:55]

Patchset 1 (id:??) landed as
https://crrev.com/f2415b13846f8217550257e85d3cb0130ddff197
Cr-Commit-Position: refs/heads/master@{#332370}