DO NOT MERGE: Resolve mBehindAlpha with mCurrentBehindAlpha

fixes a build breakage, mBehindAlpha is a master thing but mCurrentBehindAlpha is a QPR1 thing

BUG: 151041066
Test: Compile
Change-Id: I78d767319d2ba856a9f453f71b39ddd3c96e6b9f
1 file changed