GpuStats: complete the coverage of ES1 usage tracking

Previously, we only track when the app explicitly creates an es1
context. This change fixes the coverage because the implicit default
context creation goes to es1.

Bug: 146661131
Test: build, flash and boot
Change-Id: I5d60812e86bd194d41c91b1e50e3a5e3c37e072d
1 file changed