Add viz-host HitTestQuery.

components/viz/hit_test/hit_test_export.h

Index: components/viz/hit_test/hit_test_export.h
diff --git a/components/viz/hit_test/hit_test_export.h b/components/viz/hit_test/hit_test_export.h
new file mode 100644
index 0000000000000000000000000000000000000000..560c52dcd05fdbe3dd4face31ec939800603d971
--- /dev/null
+++ b/components/viz/hit_test/hit_test_export.h
@@ -0,0 +1,29 @@
+// Copyright 2017 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.
+
+#ifndef COMPONENTS_VIZ_HIT_TEST_HIT_TEST_EXPORT_H_
+#define COMPONENTS_VIZ_HIT_TEST_HIT_TEST_EXPORT_H_
+
+#if defined(COMPONENT_BUILD)
+#if defined(WIN32)
+
+#if defined(HIT_TEST_IMPLEMENTATION)
+#define HIT_TEST_EXPORT __declspec(dllexport)
+#else
+#define HIT_TEST_EXPORT __declspec(dllimport)
+#endif  // defined(HIT_TEST_IMPLEMENTATION)
+
+#else  // defined(WIN32)
+#if defined(HIT_TEST_IMPLEMENTATION)
+#define HIT_TEST_EXPORT __attribute__((visibility("default")))
+#else
+#define HIT_TEST_EXPORT
+#endif
+#endif
+
+#else  // defined(COMPONENT_BUILD)
+#define HIT_TEST_EXPORT
+#endif
+
+#endif  // COMPONENTS_VIZ_HITTEST_HITTEST_EXPORT_H_