Fix skiaserve crash when displaying batch bounds

tools/debugger/SkDebugCanvas.cpp

Index: tools/debugger/SkDebugCanvas.cpp
diff --git a/tools/debugger/SkDebugCanvas.cpp b/tools/debugger/SkDebugCanvas.cpp
index 123b9b4aa874279ae684f4e0e04ee0744467e84c..6b629c8959ffcb4ac70ed45e8a529fdaa897874b 100644
--- a/tools/debugger/SkDebugCanvas.cpp
+++ b/tools/debugger/SkDebugCanvas.cpp
@@ -239,6 +239,11 @@ void SkDebugCanvas::drawTo(SkCanvas* canvas, int index, int m) {
         }
 
 #if SK_SUPPORT_GPU
+        // We need to flush any pending operations, or they might batch with commands below.
+        // Previous operations were not registered with the audit trail when they were
+        // created, so if we allow them to combine, the audit trail will fail to find them.
+        canvas->flush();
+
         GrAuditTrail::AutoCollectBatches* acb = nullptr;
         if (at) {
             acb = new GrAuditTrail::AutoCollectBatches(at, i);