Fix skiaserve crash when displaying batch bounds

tools/debugger/SkDebugCanvas.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvasPriv.h"
 #include "SkClipStack.h"
 #include "SkDebugCanvas.h"
@@ skipping 221 matching lines @@
         at = this->getAuditTrail(canvas);
     }
 #endif
 
     for (int i = 0; i <= index; i++) {
         if (i == index && fFilter) {
             canvas->clear(0xAAFFFFFF);
         }
 
 #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);
         }
 #endif
 
         if (fCommandVector[i]->isVisible()) {
             if (fMegaVizMode && fCommandVector[i]->active()) {
                 // "active" commands execute their visualization behaviors:
                 //     All active saveLayers get replaced with saves so all draws go to the
@@ skipping 550 matching lines @@
 }
 
 bool SkDebugCanvas::lastClipStackData(const SkPath& devPath) {
     if (fCalledAddStackData) {
         fClipStackData.appendf("<br>");
         addPathData(devPath, "pathOut");
         return true;
     }
     return false;
 }