Began logging more gpu stats from nanobench

bench/SKPBench.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SKPBench.h"
 #include "SkCommandLineFlags.h"
 #include "SkMultiPictureDraw.h"
@@ skipping 137 matching lines @@
     for (int j = 0; j < fTileRects.count(); ++j) {
         const SkMatrix trans = SkMatrix::MakeTrans(-fTileRects[j].fLeft / fScale,
                                                    -fTileRects[j].fTop / fScale);
         fSurfaces[j]->getCanvas()->drawPicture(fPic, &trans, nullptr);
     }
 
     for (int j = 0; j < fTileRects.count(); ++j) {
         fSurfaces[j]->getCanvas()->flush();
     }
 }
+
+#if SK_SUPPORT_GPU
+static void draw_pic_for_stats(SkCanvas* canvas, GrContext* context, const SkPicture* picture,
+                               SkTArray<SkString>* keys, SkTArray<double>* values,
+                               const char* tag) {
+    context->resetGpuStats();
+    canvas->drawPicture(picture);
+    canvas->flush();
+
+    int offset = keys->count();
+    context->dumpGpuStatsKeyValuePairs(keys, values);
+
+    // append tag, but only to new tags
+    for (int i = offset; i < keys->count(); i++, offset++) {
+        (*keys)[i].appendf("_%s", tag);
+    }
+}
+#endif
+
+void SKPBench::getGpuStats(SkCanvas* canvas, SkTArray<SkString>* keys, SkTArray<double>* values) {
+#if SK_SUPPORT_GPU
+    // we do a special single draw and then dump the key / value pairs
+    GrContext* context = canvas->getGrContext();
+    if (!context) {
+        return;
+    }
+
+    // TODO refactor this out if we want to test other subclasses of skpbench
+    context->flush();
+    context->freeGpuResources();
+    context->resetContext();
+    draw_pic_for_stats(canvas, context, fPic, keys, values, "first_frame");
+
+    // draw second frame
+    draw_pic_for_stats(canvas, context, fPic, keys, values, "second_frame");
+
+#endif
+}