Check opaque size in CREATE_PLUGIN.

Check opaque size to be not greater than an abitrary 100K
and verify malloc succeeded.

Test: Play Movies & TV

Test: Netflix

Test: ANDROID_BUILD_TOP= ./android-gts/tools/gts-tradefed run gts
 -m GtsMediaTestCases --test
com.google.android.media.gts.WidevineH264PlaybackTests#testL1With480P60

Test: Forcing opaque size to exceed limit and malloc to report failure;
  both resulted in Netflix reporting an error and failing to play.
  This is the expected result.

bug: 30202440
Change-Id: I9fdaf208471f2781ffbd656358b1bf1ef5b28ee8