Rename transform_converters.* to transform_type_converters.*.

Rename transform_converters.* to transform_type_converters.*.

These files declare/define mojo TypeConverters, so the file names
should reflect that.

R=jamesr@chromium.org,msw@chromium.org
BUG=457280
Committed: https://crrev.com/6830d8f0dd0c9cb3b026ba1126525400be766792
Cr-Commit-Position: refs/heads/master@{#317619}

[jamesr, 2015-02-23 19:07:11]

lgtm

[wtc, 2015-02-23 19:17:15]

The CQ bit was checked by wtc@chromium.org

[msw, 2015-02-23 19:17:41]

lgtm

[commit-bot: I haz the power, 2015-02-23 19:18:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/950573002/1

[commit-bot: I haz the power, 2015-02-23 19:22:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-23 19:22:59]

Patchset 1 (id:??) landed as
https://crrev.com/6830d8f0dd0c9cb3b026ba1126525400be766792
Cr-Commit-Position: refs/heads/master@{#317619}