Spruce up batch info printouts

src/gpu/GrDrawingManager.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDrawContext.h"
 #include "GrDrawingManager.h"
 #include "GrDrawTarget.h"
@@ skipping 49 matching lines @@
 void GrDrawingManager::flush() {
     if (fFlushing || this->wasAbandoned()) {
         return;
     }
     fFlushing = true;
 
     SkDEBUGCODE(bool result =)
                         SkTTopoSort<GrDrawTarget, GrDrawTarget::TopoSortTraits>(&fDrawTargets);
     SkASSERT(result);
 
+    // Enable this to print out verbose batching information
 #if 0
     for (int i = 0; i < fDrawTargets.count(); ++i) {
         SkDEBUGCODE(fDrawTargets[i]->dump();)
     }
 #endif
 
     for (int i = 0; i < fDrawTargets.count(); ++i) {
         fDrawTargets[i]->prepareBatches(&fFlushState);
     }
 
@@ skipping 99 matching lines @@
                                                         fContext, this, std::move(rt), 
                                                         surfaceProps,
                                                         fContext->getAuditTrail(), fSingleOwner));
         }
     }
 
     return sk_sp<GrDrawContext>(new GrDrawContext(fContext, this, std::move(rt), surfaceProps,
                                                   fContext->getAuditTrail(),
                                                   fSingleOwner));
 }