add a ClassID function to GrBatch

src/gpu/batches/GrBatch.cpp

Index: src/gpu/batches/GrBatch.cpp
diff --git a/src/gpu/batches/GrBatch.cpp b/src/gpu/batches/GrBatch.cpp
index a3a9884b0fd7f6178db1f5465ad51fbf9d2f0531..19c19ffcf1d05d1d988a4c6172ff507c05a811c0 100644
--- a/src/gpu/batches/GrBatch.cpp
+++ b/src/gpu/batches/GrBatch.cpp
@@ -46,10 +46,10 @@ void GrBatch::operator delete(void* target) {
     return MemoryPoolAccessor().pool()->release(target);
 }
 
-GrBatch::GrBatch()
-    : fClassID(kIllegalBatchID)
+GrBatch::GrBatch(uint32_t classID)
+    : fClassID(classID)
 #if GR_BATCH_SPEW
-    , fUniqueID(GenID(&gCurrBatchUniqueID))
+    , fUniqueID(GenBatchID())
 #endif
 {
     SkDEBUGCODE(fUsed = false;)