Exclude java classes that no longer needed with Gvr's Java dynamic loading

Bug: 764441
Change-Id: Iea755b93f9f6506603dee28f10cf06c88a63d109
Reviewed-on: https://chromium-review.googlesource.com/775145Reviewed-by: Brandon Jones <bajones@chromium.org>
Commit-Queue: Biao She <bshe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517853}

third_party/gvr-android-sdk/proguard-gvr-chromium.txt

 -dontwarn com.google.common.logging.nano.Vr$**
+-dontwarn com.google.vr.**