extract some common code from PictureRenderer

src/utils/SkDataUtils.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 "SkData.h"
+#include "SkDataUtils.h"
+#include "SkStream.h"
+
+/*static*/ SkData* SkDataUtils::ReadIntoSkData(SkStream &stream, size_t maxBytes) {
+    if (0 == maxBytes) {
+        return SkData::NewEmpty();
+    }
+    char* bufStart = reinterpret_cast<char *>(sk_malloc_throw(maxBytes));
+    char* bufPtr = bufStart;
+    size_t bytesRemaining = maxBytes;
+    while (bytesRemaining > 0) {
+        size_t bytesReadThisTime = stream.read(bufPtr, bytesRemaining);
+        if (0 == bytesReadThisTime) {
+            break;
+        }
+        bytesRemaining -= bytesReadThisTime;
+        bufPtr += bytesReadThisTime;
+    }
+    return SkData::NewFromMalloc(bufStart, maxBytes - bytesRemaining);
+}