Add samplingTime mode to nanobench

tools/Stats.h

 #ifndef Stats_DEFINED
 #define Stats_DEFINED
 
 #include "SkString.h"
 #include "SkTSort.h"
 
 #ifdef SK_BUILD_FOR_WIN
     static const char* kBars[] = { ".", "o", "O" };
 #else
     static const char* kBars[] = { "▁", "▂", "▃", "▄", "▅", "▆", "▇", "█" };
 #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++) {
             if (samples[i] < min) { min = samples[i]; }
             if (samples[i] > max) { max = samples[i]; }
         }
 
         double sum = 0.0;
         for (int i = 0 ; i < n; i++) {
             sum += samples[i];
         }
         mean = sum / n;
 
         double err = 0.0;
         for (int i = 0 ; i < n; i++) {
             err += (samples[i] - mean) * (samples[i] - mean);
         }
         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];
 
         // Normalize samples to [min, max] in as many quanta as we have distinct bars to print.
         for (int i = 0; i < n; i++) {
             if (min == max) {
                 // All samples are the same value.  Don't divide by zero.
                 plot.append(kBars[0]);
                 continue;
             }
@@ skipping 10 matching lines @@
 
     double min;
     double max;
     double mean;    // Estimate of population mean.
     double var;     // Estimate of population variance.
     double median;
     SkString plot;  // A single-line bar chart (_not_ histogram) of the samples.
 };
 
 #endif//Stats_DEFINED