Add the Windows.IsPinnedToTaskbar metric.

chrome/common/shell_handler_win.mojom

Index: chrome/common/shell_handler_win.mojom
diff --git a/chrome/common/shell_handler_win.mojom b/chrome/common/shell_handler_win.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..b16648d6064b4353ccc4c2c4bc34cc42f0268c46
--- /dev/null
+++ b/chrome/common/shell_handler_win.mojom
@@ -0,0 +1,10 @@
+// Copyright 2016 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.
+
+module mojom;
+
+interface ShellHandler {
+  // Returns the pinned state of the current executable.
+  IsPinnedToTaskbar() => (bool succeeded, bool is_pinned_to_taskbar);
+};