Add flag to force gpu trace markers to be used and printed out for debugging.

Add flag to force gpu trace markers to be used and printed out for debugging.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/bdad9c34d8f15362d17ba8d7a9fb202b1f3a2ef3

[egdaniel, 2015-03-05 17:48:56]

egdaniel@google.com changed reviewers:
+ robertphillips@google.com

[egdaniel, 2015-03-05 17:48:57]

ptal

[robertphillips, 2015-03-05 17:50:26]

lgtm

[egdaniel, 2015-03-05 17:51:07]

The CQ bit was checked by egdaniel@google.com

[commit-bot: I haz the power, 2015-03-05 17:52:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/976413002/20001

[commit-bot: I haz the power, 2015-03-05 17:52:47]

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

[commit-bot: I haz the power, 2015-03-05 17:52:48]

Presubmit check for 976413002-20001 failed and returned exit status 1.

Running presubmit commit checks ...

** Presubmit ERRORS **
Since the CL is editing public API, you must have an LGTM from one of:
('reed@chromium.org', 'reed@google.com', 'bsalomon@chromium.org',
'bsalomon@google.com', 'djsollen@chromium.org', 'djsollen@google.com')

[egdaniel, 2015-03-05 17:54:05]

egdaniel@google.com changed reviewers:
+ bsalomon@google.com

[bsalomon, 2015-03-05 20:09:58]

On 2015/03/05 17:54:05, egdaniel wrote:

lgtm

[egdaniel, 2015-03-05 20:12:19]

The CQ bit was checked by egdaniel@google.com

[commit-bot: I haz the power, 2015-03-05 20:13:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/976413002/20001

[commit-bot: I haz the power, 2015-03-05 20:19:20]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/bdad9c34d8f15362d17ba8d7a9fb202b1f3a2ef3