Add palette tool/manager.

ash/common/system/chromeos/palette/palette_tool.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_SYSTEM_CHROMEOS_PALETTE_PALETTE_TOOL_H_
+#define ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_PALETTE_TOOL_H_
+
+#include <map>
+#include <memory>
+#include <vector>
+
+#include "ash/ash_export.h"
+#include "base/callback.h"
+#include "base/macros.h"
+
+namespace views {
+class View;
+}
+
+namespace ash {
+
+class WmWindow;
+
+enum class PaletteGroup;
+enum class PaletteToolId;
+class PaletteToolManager;
+
+class ASH_EXPORT PaletteTool {

[Evan Stade, 2016/07/13 18:34:01]

class needs docs

[jdufault, 2016/07/13 19:22:39]

Done.

+ public:
+  using ToolAction = base::Callback<void(PaletteToolId)>;
+
+  static void RegisterToolInstances(PaletteToolManager* tool_manager);
+
+  PaletteTool();
+  virtual ~PaletteTool();
+
+  // Initialize the tool. It is assumed this is called from a PaletteToolManager
+  // instance.
+  void Initialize(WmWindow* window,
+                  const ToolAction& enable_tool,
+                  const ToolAction& disable_tool);
+
+  virtual PaletteGroup group() const = 0;
+  virtual PaletteToolId tool_id() const = 0;
+
+  // Called when the user activates the tool. Only one tool per group can be
+  // active at any given time.
+  virtual void OnEnable();
+  // Disable the tool, either because this tool called DisableSelf(), the
+  // user cancelled the tool, or the user activated another tool within the
+  // same group.
+  virtual void OnDisable();
+
+  // Create a view that will be used in the palette. The view is owned by the
+  // caller. DestroyView is called when the view has been deallocated by its
+  // owner.
+  virtual views::View* CreateView() = 0;
+  virtual void DestroyView() = 0;

[Evan Stade, 2016/07/13 18:34:01]

more like ViewDestroyed

[jdufault, 2016/07/13 19:22:39]

Done - the idea was to mirror SystemTrayItem, but I also strongly prefer this
name.

+
+ protected:
+  // Enables/disables the tool.
+  bool enabled() const;
+  void EnableSelf();
+  void DisableSelf();
+
+  // Window this tool is associated with.
+  WmWindow* window() const;
+
+ private:
+  bool enabled_ = false;
+  ToolAction enable_tool_;
+  ToolAction disable_tool_;
+  WmWindow* window_;
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_PALETTE_TOOL_H_