Simplify GrDrawBatch uploads and token uage.

GrVertexBatch subclasses no longer need "initDraw".

Simplifies GrTestBatch

BUG=skia:
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Review URL: https://codereview.chromium.org/1835283002
diff --git a/src/gpu/GrBatchFlushState.cpp b/src/gpu/GrBatchFlushState.cpp
index f01d888..c4ba264 100644
--- a/src/gpu/GrBatchFlushState.cpp
+++ b/src/gpu/GrBatchFlushState.cpp
@@ -12,11 +12,10 @@
 
 GrBatchFlushState::GrBatchFlushState(GrGpu* gpu, GrResourceProvider* resourceProvider)
     : fGpu(gpu)
-    , fUploader(gpu)
     , fResourceProvider(resourceProvider)
     , fVertexPool(gpu)
     , fIndexPool(gpu)
-    , fCurrentToken(0)
+    , fLastIssuedToken(GrBatchDrawToken::AlreadyFlushedToken())
     , fLastFlushedToken(0) {}
 
 void* GrBatchFlushState::makeVertexSpace(size_t vertexSize, int vertexCount,