Browsing Data Deletion: Style fixes

Browsing Data Deletion: Style fixes

These nits were noted when a new storage type was added in
crrev.com/394063003 and this CL applies those style changes and other
suggestions to the other files. Standardize on DCHECK(!x), use
DCHECK_CURRENTLY_ON() where possible, use empty() rather than !size(),
all the trivial cpplint.py findings, and add/use ASSERTs in mock
classes (vs. CHECK/DCHECKs)

No functional changes.

R=bauerb@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289010

[Bernhard Bauer, 2014-08-12 13:39:10]

Thanks for the cleanup! LGTM

[jsbell, 2014-08-12 14:24:37]

The CQ bit was checked by jsbell@chromium.org

[commit-bot: I haz the power, 2014-08-12 14:25:45]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jsbell@chromium.org/459233002/20001

[commit-bot: I haz the power, 2014-08-12 17:17:29]

Change committed as 289010