Fix GPU cmd tests so they pass ASAN

gpu/command_buffer/common/gles2_cmd_format_test.cc

-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file contains unit tests for gles2 commmands
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "gpu/command_buffer/common/gles2_cmd_format.h"
 
 namespace gpu {
 namespace gles2 {
 
+class GLES2FormatTest : public testing::Test {
+ protected:
+  static const unsigned char kInitialValue = 0xBD;
+
+  virtual void SetUp() {
+    memset(buffer_, kInitialValue, sizeof(buffer_));
+  }
+
+  virtual void TearDown() {
+  }
+
+  template <typename T>
+  T* GetBufferAs() {
+    return static_cast<T*>(static_cast<void*>(&buffer_));
+  }
+
+  void CheckBytesWritten(
+      const void* end, size_t expected_size, size_t written_size) {
+    size_t actual_size = static_cast<const unsigned char*>(end) -
+        GetBufferAs<const unsigned char>();
+    EXPECT_LT(actual_size, sizeof(buffer_));
+    EXPECT_GT(actual_size, 0u);
+    EXPECT_EQ(expected_size, actual_size);
+    EXPECT_EQ(kInitialValue, buffer_[written_size]);
+    EXPECT_NE(kInitialValue, buffer_[written_size - 1]);
+  }
+
+  void CheckBytesWrittenMatchesExpectedSize(
+      const void* end, size_t expected_size) {
+    CheckBytesWritten(end, expected_size, expected_size);
+  }
+
+ private:
+  unsigned char buffer_[1024];
+};
+
+// GCC requires these declarations, but MSVC requires they not be present
+#ifndef _MSC_VER
+const unsigned char GLES2FormatTest::kInitialValue;
+#endif
+
 #include "gpu/command_buffer/common/gles2_cmd_format_test_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu