Fix context creation problems in dm

Fixes these issues:

1. The glXCreateContextAttribsARB call seems to modify the
context_attrib parameter upon failure. Since context_attrib was static,
if it first tried to create an OpenGL 4.4 context and it failed, further
attempts to create a context with lower versions would also fail.

2. Getting an OpenGL 3.0 context was never tried.

3. Context creation for ES 3.0 was failing on my machine. Since ES 2.0
looks like the intended version from the surrounding code, I set it to
that. It could be rewritten to use a similar loop as standard OpenGL and
try from the highest version to the lowest.

BUG=skia:5403
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2147513002

Review-Url: https://codereview.chromium.org/2147513002

0 files changed, 0 insertions, 0 deletions