Add CSS agent for various window/widget/view attributes in devtools

ash/common/devtools/ash_devtools_css_agent.h

+// 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.
+
+#ifndef ASH_COMMON_DEVTOOLS_ASH_DEVTOOLS_CSS_AGENT_H_
+#define ASH_COMMON_DEVTOOLS_ASH_DEVTOOLS_CSS_AGENT_H_
+
+#include "ash/common/devtools/ash_devtools_dom_agent.h"
+#include "components/ui_devtools/CSS.h"
+
+namespace ash {
+namespace devtools {
+
+class ASH_EXPORT AshDevToolsCSSAgent
+    : public NON_EXPORTED_BASE(ui::devtools::UiDevToolsBaseAgent<
+                               ui::devtools::protocol::CSS::Metainfo>) {
+ public:
+  explicit AshDevToolsCSSAgent(AshDevToolsDOMAgent* dom_agent);
+  ~AshDevToolsCSSAgent() override;
+
+  // CSS::Backend
+  ui::devtools::protocol::Response getMatchedStylesForNode(
+      int nodeId,
+      ui::devtools::protocol::Maybe<ui::devtools::protocol::CSS::CSSStyle>*
+          inlineStyle) override;
+
+ private:
+  std::unique_ptr<ui::devtools::protocol::CSS::CSSStyle> GetStylesForNode(
+      int nodeId);
+
+  AshDevToolsDOMAgent* dom_agent_;
+
+  DISALLOW_COPY_AND_ASSIGN(AshDevToolsCSSAgent);
+};
+
+}  // namespace devtools
+}  // namespace ash
+
+#endif  // ASH_COMMON_DEVTOOLS_ASH_DEVTOOLS_CSS_AGENT_H_