[Cast] Fix log_deserializer BasePacketEvent merge bug.

[Cast] Fix log_deserializer BasePacketEvent merge bug.

The bug is that if we are merging BasePacketEvent A into B, and A had
a valid packet size but B did not (i.e. because it only has receiver
events and therefore no packet size) then the merged result would take
on the packet size of B which is invalid.

The fix is to take the max of the sizes of A and B and set it on the
merged result.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=278421

[Alpha Left Google, 2014-06-18 23:35:34]

lgtm

[commit-bot: I haz the power, 2014-06-18 23:37:00]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/imcheng@chromium.org/331383006/1

[commit-bot: I haz the power, 2014-06-19 09:08:50]

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

[commit-bot: I haz the power, 2014-06-19 09:08:51]

Try jobs failed on following builders:
  android_dbg_triggered_tests on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg_triggered...)

[imcheng, 2014-06-19 16:32:12]

The CQ bit was checked by imcheng@chromium.org

[commit-bot: I haz the power, 2014-06-19 16:33:57]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/imcheng@chromium.org/331383006/1

[commit-bot: I haz the power, 2014-06-19 17:59:47]

Change committed as 278421