This fixes clients with custom JNI_OnLoad code. This is basically a reland of https://webrtc-review.googlesource.com/21281, but called from LoadGlobalClassReferenceHolder instead of InitGlobalJniVariables. The problem it solves is that some clients call InitGlobalJniVariables from a strange thread and without using the rest of our Java API. TBR=lliuu@@webrtc.org,sakal@webrtc.org Bug: webrtc:8278 Change-Id: I664e50920bcd7e087ec2d8bb5be13569e8ff3088 Reviewed-on: https://webrtc-review.googlesource.com/22801 Reviewed-by: Magnus Jedvert <magjed@webrtc.org> Commit-Queue: Magnus Jedvert <magjed@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20663}