Split cursor location from UserDisplayManager.

services/ui/ws/cursor_location_manager.cc

+// 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.
+
+#include "services/ui/ws/cursor_location_manager.h"
+
+namespace ui {
+namespace ws {
+
+CursorLocationManager::CursorLocationManager() {}
+
+CursorLocationManager::~CursorLocationManager() {}
+
+void CursorLocationManager::OnMouseCursorLocationChanged(
+    const gfx::Point& point) {
+  current_cursor_location_ = static_cast<base::subtle::Atomic32>(
+      (point.x() & 0xFFFF) << 16 | (point.y() & 0xFFFF));
+  if (cursor_location_memory()) {
+    base::subtle::NoBarrier_Store(cursor_location_memory(),
+                                  current_cursor_location_);
+  }
+}
+
+mojo::ScopedSharedBufferHandle
+CursorLocationManager::GetCursorLocationMemory() {
+  if (!cursor_location_handle_.is_valid()) {
+    // Create our shared memory segment to share the cursor state with our
+    // window clients.
+    cursor_location_handle_ =
+        mojo::SharedBufferHandle::Create(sizeof(base::subtle::Atomic32));
+
+    if (!cursor_location_handle_.is_valid())
+      return mojo::ScopedSharedBufferHandle();
+
+    cursor_location_mapping_ =
+        cursor_location_handle_->Map(sizeof(base::subtle::Atomic32));
+    if (!cursor_location_mapping_)
+      return mojo::ScopedSharedBufferHandle();
+    base::subtle::NoBarrier_Store(cursor_location_memory(),
+                                  current_cursor_location_);
+  }
+
+  return cursor_location_handle_->Clone(
+      mojo::SharedBufferHandle::AccessMode::READ_ONLY);
+}
+
+}  // namespace ws
+}  // namespace ui