Implement the new magnifier effect.

 - Uses drawBitmapMesh to mimic the fisheye effect.
 - Avoids any logic changes to the old style magnifier.
 - The new magnifier is not exposed to public.
 - Creates the magnifier instance lazily.
 - Minor code cleanups suggested by IDE.

Bug: 145555868
Test: manually tested.
Change-Id: I6f6f6b353e2ce53bdc97fb36dd25cafa14d3d779