Allow the user to cancel the capture region action, and show its active status in the tray.

ash/common/system/chromeos/palette/palette_tool_manager.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_MANAGER_H_
 #define ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_PALETTE_TOOL_MANAGER_H_
 
 #include <map>
 #include <memory>
 #include <vector>
@@ skipping 49 matching lines @@
   // deactivated state. This class takes ownership over |tool|.
   void AddTool(std::unique_ptr<PaletteTool> tool);
 
   // Activates tool_id and deactivates any other active tool in the same
   // group as tool_id.
   void ActivateTool(PaletteToolId tool_id);
 
   // Deactivates the given tool.
   void DeactivateTool(PaletteToolId tool_id);
 
-  // Optional methods that are not likely to be needed, but will be
-  // implemented if necessary.
+  // Returns true if the given tool is active.
   bool IsToolActive(PaletteToolId tool_id);
+
+  // Returns the active tool for the given group.
   PaletteToolId GetActiveTool(PaletteGroup group);
 
   // Fetch the active tray icon for the given tool. Returns
   // gfx::VectorIconId::VECTOR_ICON_NONE if not available.
   gfx::VectorIconId GetActiveTrayIcon(PaletteToolId tool_id);
 
   // Create views for all of the registered tools.
   std::vector<PaletteToolView> CreateViews();
 
   // Called when the views returned by CreateViews have been destroyed. This
@@ skipping 17 matching lines @@
 
   // Owned list of all tools.
   std::vector<std::unique_ptr<PaletteTool>> tools_;
 
   DISALLOW_COPY_AND_ASSIGN(PaletteToolManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_PALETTE_TOOL_MANAGER_H_