Refactor gpu code generation

Refactor gpu code generation

Make CWriter and CHeaderWriter more pythonic - use the 'with' statement
to automatically close the file. The 'write' function now writes
directly into the file and not into a string.

Bug=None

Committed: https://crrev.com/a5535301ce813d9f709c4f7cee1f5d1bc975cb3f
Cr-Commit-Position: refs/heads/master@{#342077}

[mkollaro, 2015-07-31 18:21:22]

martina.kollarova@intel.com changed reviewers:
+ bajones@chromium.org, piman@chromium.org

[mkollaro, 2015-07-31 18:21:23]

Most of the changes are just the extra indent caused by the 'with' statement, I
recommend viewing it with "git diff --ignore-all-space".

[piman, 2015-08-03 21:25:50]

piman@chromium.org changed reviewers:
+ zmo@chromium.org

[piman, 2015-08-03 21:25:50]

piman->zmo

[mkollaro, 2015-08-05 11:56:41]

The CQ bit was checked by martina.kollarova@intel.com to run a CQ dry run

[commit-bot: I haz the power, 2015-08-05 11:56:48]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1265023002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1265023002/20001

[commit-bot: I haz the power, 2015-08-05 11:56:50]

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

[commit-bot: I haz the power, 2015-08-05 11:56:50]

Dry run: No L-G-T-M from a valid reviewer yet. Only full committers are
accepted.
Even if an L-G-T-M may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Zhenyao Mo, 2015-08-06 03:38:32]

LGTM

[Zhenyao Mo, 2015-08-06 03:39:08]

On 2015/08/06 03:38:32, Zhenyao Mo wrote:
> LGTM

Sorry about the delay, but the shifting makes it really hard to see where the
changes are made.

[mkollaro, 2015-08-06 08:11:32]

The CQ bit was checked by martina.kollarova@intel.com

[commit-bot: I haz the power, 2015-08-06 08:11:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1265023002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1265023002/20001

[commit-bot: I haz the power, 2015-08-06 08:19:53]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-06 08:20:50]

Patchset 2 (id:??) landed as
https://crrev.com/a5535301ce813d9f709c4f7cee1f5d1bc975cb3f
Cr-Commit-Position: refs/heads/master@{#342077}