Add option to draw wireframe batch bounds

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 2861ae8ea230b44734fa54d238dbe9738b9580fb..26ba13b5476b165edc0c9aa1ce309224cfb1da7a 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -807,6 +807,7 @@ void PreAbandonGpuContextErrorHandler(SkError, void*) {}
 
 DEFINE_bool(imm, false, "Run gpu configs in immediate mode.");
 DEFINE_bool(batchClip, false, "Clip each GrBatch to its device bounds for testing.");
+DEFINE_bool(batchBounds, false, "Draw a wireframe bounds of each GrBatch.");
 
 Error GPUSink::draw(const Src& src, SkBitmap* dst, SkWStream*, SkString* log) const {
     GrContextOptions options;
@@ -816,6 +817,9 @@ Error GPUSink::draw(const Src& src, SkBitmap* dst, SkWStream*, SkString* log) co
     if (FLAGS_batchClip) {
         options.fClipBatchToBounds = true;
     }
+    if (FLAGS_batchBounds) {
+        options.fDrawBatchBounds = true;
+    }
     src.modifyGrContextOptions(&options);
 
     GrContextFactory factory(options);