[Merge] [Win, Linux] Always display the avatar button text at the same size.

[Merge] [Win, Linux] Always display the avatar button text at the same size.

The problem is that some locales (Hindi) or platforms (Linux) have a
bigger base font size for the default font (crbug.com/405994). If this
is the case, we should decrease the font size to the one we expect,
so that the font fits in the button correctly.

Just adjusting the baseline is not always enough, as the new avatar
button has a fixed size, and the text might not fit correctly
regardless of the baseline adjustments.

Screenshots: https://drive.google.com/folderview?id=0B1B1Up4p2NRMRHc5WTBxZWNrRm8&usp=sharing

BUG=403466
TBR=noms@chromium.org
TEST=Start Chrome with --enable-new-avatar-menu on Linux, or with --enable-new-avatar-menu and --lang-hi on Windows. The avatar button text should fit nicely in the button.

Review URL: https://codereview.chromium.org/470053004

Cr-Commit-Position: refs/heads/master@{#292715}
(cherry picked from commit 899ae44e331661f709f463d6861a1dbceb9194f2)

Committed to pending queue: https://chromium.googlesource.com/chromium/src/+/f8e6698

[noms (inactive), 2014-09-02 19:04:36]

Committed patchset #1 (id:1) to pending queue manually as f8e6698 (presubmit
successful).