Add samplingTime mode to nanobench

Adds a nanobench mode that takes samples for a fixed amount of time,
rather than taking a fixed amount of samples.

BUG=skia:

Review URL: https://codereview.chromium.org/1204153002

2 files changed, 16 insertions, 3 deletions

diff --git a/tools/Stats.h b/tools/Stats.h
index 8487a9497d..12c1d35e1f 100644
--- a/tools/Stats.h
+++ b/tools/Stats.h
@@ -1,3 +1,10 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
 #ifndef Stats_DEFINED
 #define Stats_DEFINED
 
@@ -11,7 +18,13 @@
 #endif
 
 struct Stats {
-    Stats(const double samples[], int n) {
+    Stats(const SkTArray<double>& samples) {
+        int n = samples.count();
+        if (!n) {
+            min = max = mean = var = median = 0;
+            return;
+        }
+
         min = samples[0];
         max = samples[0];
         for (int i = 0; i < n; i++) {
@@ -32,7 +45,7 @@ struct Stats {
         var = err / (n-1);
 
         SkAutoTMalloc<double> sorted(n);
-        memcpy(sorted.get(), samples, n * sizeof(double));
+        memcpy(sorted.get(), samples.begin(), n * sizeof(double));
         SkTQSort(sorted.get(), sorted.get() + n - 1);
         median = sorted[n/2];
 
diff --git a/tools/VisualBench.cpp b/tools/VisualBench.cpp
index cbc8994592..ac53b43167 100644
--- a/tools/VisualBench.cpp
+++ b/tools/VisualBench.cpp
@@ -152,7 +152,7 @@ void VisualBench::printStats() {
         SkDebugf("%s\n", shortName.c_str());
     } else {
         SkASSERT(measurements.count());
-        Stats stats(measurements.begin(), measurements.count());
+        Stats stats(measurements);
         const double stdDevPercent = 100 * sqrt(stats.var) / stats.mean;
         SkDebugf("%4d/%-4dMB\t%d\t%d\t%s\t%s\t%s\t%s\t%.0f%%\t%s\n",
                  sk_tools::getCurrResidentSetSizeMB(),