HID: Support top-level collection usages in device info.

device/hid/hid_report_descriptor.h

Index: device/hid/hid_report_descriptor.h
diff --git a/device/hid/hid_report_descriptor.h b/device/hid/hid_report_descriptor.h
new file mode 100644
index 0000000000000000000000000000000000000000..fa67fa43c291aa033bb648bbf38faeacc0618d80
--- /dev/null
+++ b/device/hid/hid_report_descriptor.h
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+// Copyright 2014 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 DEVICE_HID_HID_REPORT_DESCRIPTOR_H_
+#define DEVICE_HID_HID_REPORT_DESCRIPTOR_H_
+
+#include <vector>
+
+#include "base/memory/linked_ptr.h"
+#include "device/hid/hid_report_descriptor_item.h"
+#include "device/hid/hid_usage_and_page.h"
+
+namespace device {
+
+// HID report descriptor.
+// See section 6.2.2 of HID specifications (v1.11).
+class HidReportDescriptor {
+
+ public:
+  HidReportDescriptor(const uint8_t* bytes, size_t size);
+  ~HidReportDescriptor();
+
+  const std::vector<linked_ptr<HidReportDescriptorItem> >& items() const {
+    return items_;
+  }
+
+  // Returns HID usages of top-level collections present in the descriptor.
+  void GetTopLevelCollections(
+      std::vector<HidUsageAndPage>* topLevelCollections);
+
+ private:
+  std::vector<linked_ptr<HidReportDescriptorItem> > items_;
+};
+
+}  // namespace device
+
+#endif  // DEVICE_HID_HID_REPORT_DESCRIPTOR_H_