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"
+#include "base/optional.h"
+#include "ui/gfx/vector_icon_types.h"
+
+namespace views {
+class View;
+}
+
+namespace ash {
+
+class WmWindow;
+
+enum class PaletteGroup;
+enum class PaletteToolId;
+class PaletteToolManager;
+
+// A PaletteTool is a generalized action inside of the palette menu in the
+// shelf. Only one tool per group is active at any given time. When the tool is
+// active, it should be showing some specializied UI. The tool is no longer
+// active if it completes its action, if the user selects another tool with the
+// same group, or if the user just cancels the action from the palette.
+class ASH_EXPORT PaletteTool {
+ public:
+  class Delegate {
+   public:
+    Delegate() {}
+    virtual ~Delegate() {}
+
+    // Enable or disable a specific tool.
+    virtual void EnableTool(PaletteToolId tool_id) = 0;
+    virtual void DisableTool(PaletteToolId tool_id) = 0;
+
+    // Hide the entire palette. This should not change any tool state.
+    virtual void HidePalette() = 0;
+
+    // Returns the root window.
+    virtual WmWindow* GetWindow() = 0;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Delegate);
+  };
+
+  // Adds all available PaletteTool instances to the tool_manager.
+  static void RegisterToolInstances(PaletteToolManager* tool_manager);
+
+  // |delegate| must outlive this tool instance.
+  explicit PaletteTool(Delegate* delegate);
+  virtual ~PaletteTool();
+
+  // The group this tool belongs to. Only one tool per group can be active at
+  // any given time.
+  virtual PaletteGroup GetGroup() const = 0;
+
+  // The unique identifier for this tool. This should be the only tool that ever
+  // has this ID.
+  virtual PaletteToolId GetToolId() 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. OnViewDestroyed is called when the view has been deallocated by its
+  // owner.
+  virtual views::View* CreateView() = 0;
+  virtual void OnViewDestroyed() = 0;
+
+  // Returns an optional icon to use in the tray if this tool is active. Only
+  // one tool should ever have an active icon at any given time.
+  virtual base::Optional<gfx::VectorIconId> GetActiveTrayIcon();
+
+ protected:
+  // Enables/disables the tool.
+  bool enabled() const { return enabled_; }
+
+  Delegate* delegate() { return delegate_; }
+
+ private:
+  bool enabled_ = false;
+
+  // Unowned pointer to the delegate. The delegate should outlive this instance.
+  Delegate* delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(PaletteTool);
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_PALETTE_TOOL_H_