TSAN: use somewhat pithier SK_ANNOTATE_UNPROTECTED_READ.

include/core/SkDynamicAnnotations.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkDynamicAnnotations_DEFINED
+#define SkDynamicAnnotations_DEFINED
+
+// We nabbed this code from the dynamic_annotations library, and in their honor
+// we check the same define.  Add other macros you use here.

[reed1, 2014/02/04 14:57:55]

I have no idea what this stuff does. Can we also nab some dox from the other
file?

+
+#if DYNAMIC_ANNOTATIONS_ENABLED
+
+extern "C" {
+// TSAN provides these hooks.
+void AnnotateIgnoreReadsBegin(const char* file, int line);
+void AnnotateIgnoreReadsEnd(const char* file, int line);
+}  // extern "C"
+
+template <typename T>
+inline T SK_ANNOTATE_UNPROTECTED_READ(const volatile T& x) {
+    AnnotateIgnoreReadsBegin(__FILE__, __LINE__);
+    T read = x;
+    AnnotateIgnoreReadsEnd(__FILE__, __LINE__);
+    return read;
+}
+
+#else  // !DYNAMIC_ANNOTATIONS_ENABLED
+
+#define SK_ANNOTATE_UNPROTECTED_READ(x) (x)
+
+#endif
+
+#endif//SkDynamicAnnotations_DEFINED