Chrome Version: (copy from chrome://version)
OS: (e.g. Win7, OSX 10.9.5, etc...)

What steps will reproduce the problem?
(1) Build chrome_public_apk_incremental.
(2) Install it on the device.
(3) Go to about://version and look at the revision.
(4) Alter the state of your branch (e.g., by doing a commit).
(5) Repeat steps (1) and (2).
(6) Go to about://version and look at the revision.

What is the expected result?

In step (6), the revision should be the commit at HEAD in (4).

What happens instead?

In step (6), the revision is the same as in (3).

Note that the build itself does update as expected, as you can verify by changing some user-visible piece of behavior in step (4) and then checking the change in step (5).