Add --zero_init to simulate zero-initialized memory in CodecBench

bench/CodecBench.cpp

Index: bench/CodecBench.cpp
diff --git a/bench/CodecBench.cpp b/bench/CodecBench.cpp
index 66831fb24c6bc16b9696c5951a291f92e09f87e6..689b2d82ae815ac0d73638211b243fe31b44e929 100644
--- a/bench/CodecBench.cpp
+++ b/bench/CodecBench.cpp
@@ -9,8 +9,12 @@
 #include "CodecBenchPriv.h"
 #include "SkBitmap.h"
 #include "SkCodec.h"
+#include "SkCommandLineFlags.h"
 #include "SkOSFile.h"
 
+// Actually zeroing the memory would throw off timing, so we just lie.
+DEFINE_bool(zero_init, false, "Pretend our destination is zero-intialized, simulating Android?");
+
 CodecBench::CodecBench(SkString baseName, SkData* encoded, SkColorType colorType,
         SkAlphaType alphaType)
     : fColorType(colorType)
@@ -50,11 +54,15 @@ void CodecBench::onDraw(int n, SkCanvas* canvas) {
     for (int i = 0; i < n; i++) {
         colorCount = 256;
         codec.reset(SkCodec::NewFromData(fData));
+        SkCodec::Options options;

[msarett, 2016/01/08 21:59:41]

Can we add this code outside of the loop?  I bet the compile hoists it, but it
would make me happier.

[mtklein_C, 2016/01/08 22:03:37]

Done.

+        if (FLAGS_zero_init) {
+            options.fZeroInitialized = SkCodec::kYes_ZeroInitialized;
+        }
 #ifdef SK_DEBUG
         const SkCodec::Result result =
 #endif
         codec->getPixels(fInfo, fPixelStorage.get(), fInfo.minRowBytes(),
-                         nullptr, colorTable, &colorCount);
+                         &options, colorTable, &colorCount);
         SkASSERT(result == SkCodec::kSuccess
                  || result == SkCodec::kIncompleteInput);
     }