Record size of scroller that user scrolls

cc/input/scroller_size.h

Index: cc/input/scroller_size.h
diff --git a/cc/input/scroller_size.h b/cc/input/scroller_size.h
new file mode 100644
index 0000000000000000000000000000000000000000..6497d1e518a4d3cd2c02a31cd6abc8939de22f11
--- /dev/null
+++ b/cc/input/scroller_size.h
@@ -0,0 +1,16 @@
+// 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 CC_INPUT_SCROLLER_SIZE_H_
+#define CC_INPUT_SCROLLER_SIZE_H_
+
+namespace cc {
+
+// Use the two constants to add scroller size related UMA metrics.
+static const int kMaxScrollerSize = 200000;  // 400px * 500px

[flackr, 2017/04/12 15:31:04]

nit: Approximately 400px * 500px

[yigu, 2017/04/13 19:11:41]

Done.

[bokan, 2017/04/18 19:24:38]

Eh...why "approximately" and not "exactly"?

[flackr, 2017/04/19 00:05:49]

Oh I was just thinking because it's an area? It could be 800x250, 100x2000, etc.

+static const int kBucketNum = 50;
+
+}  // namespace cc
+
+#endif  // CC_INPUT_SCROLLER_SIZE_H_