Handle missing json resource gracefully in 3dgm
Handle missing json resource gracefully in 3dgm

If the json resource is not found (it is not currently packaged with the
APK), Viewer crashes.

TBR=
Change-Id: I0a0bdf7f97fdac8afc84d539c88d2a391e54855c
Reviewed-on: https://skia-review.googlesource.com/134515
Reviewed-by: Florin Malita <a8262bf13ea8c26821e91ea9bca6740a77c96dcd@chromium.org>
Commit-Queue: Florin Malita <a8262bf13ea8c26821e91ea9bca6740a77c96dcd@chromium.org>

aosp-mirror/platform_external_skia,google/skia,google/skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,rubenvb/skia,HalCanary/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,rubenvb/skia,aosp-mirror/platform_external_skia,rubenvb/skia,rubenvb/skia,aosp-mirror/platform_external_skia,rubenvb/skia,HalCanary/skia-hc,rubenvb/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,google/skia,rubenvb/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,google/skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,google/skia,Hikari-no-Tenshi/android_external_skia,google/skia,HalCanary/skia-hc,google/skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,google/skia