Fix constructor parameters shadowing member variables

Using the same name for the constructor parameter and the member
variable causes a warning that was being hidden by the use of -isystem
to include frameworks/native/include.  Prefix the parameter with an
underscore.

Bug: 31752268
Test: m -j
Change-Id: I60c7dc388999bafbb97cb42f5e0af5361df68d56
(cherry picked from commit 0ed088bd)