[refactor] content::TextInputManager - Make some methods const and initialize/cleanup IME maps

content/browser/renderer_host/text_input_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 CONTENT_BROWSER_RENDERER_HOST_TEXT_INPUT_MANAGER_H__
 #define CONTENT_BROWSER_RENDERER_HOST_TEXT_INPUT_MANAGER_H__
 
 #include <unordered_map>
 #include <utility>
 
@@ skipping 58 matching lines @@
 
   // ---------------------------------------------------------------------------
   // The following methods can be used to obtain information about IME-related
   // state for the active RenderWidgetHost. If the active widget is nullptr, the
   // methods below will return nullptr as well.
   // Users of these methods should not hold on to the pointers as they become
   // dangling if the TextInputManager or |active_view_| are destroyed.
 
   // Returns the currently stored TextInputState. An state of nullptr can be
   // interpreted as a ui::TextInputType of ui::TEXT_INPUT_TYPE_NONE.
-  const TextInputState* GetTextInputState();
+  const TextInputState* GetTextInputState() const;
 
   // Returns the rect between selection bounds.
-  gfx::Rect GetSelectionBoundsRect();
+  gfx::Rect GetSelectionBoundsRect() const;
 
   // Returns a vector of rects representing the character bounds.
-  const std::vector<gfx::Rect>* GetCompositionCharacterBounds();
+  const std::vector<gfx::Rect>* GetCompositionCharacterBounds() const;
 
   // ---------------------------------------------------------------------------
   // The following methods are called by RWHVs on the tab to update their IME-
   // related state.
 
   // Updates the TextInputState for |view|.
   void UpdateTextInputState(RenderWidgetHostViewBase* view,
                             const TextInputState& state);
 
   // The current IME composition has been cancelled on the renderer side for
@@ skipping 68 matching lines @@
   };
 
   void NotifyObserversAboutInputStateUpdate(RenderWidgetHostViewBase* view,
                                             bool did_update_state);
 
   // The view with active text input state, i.e., a focused <input> element.
   // It will be nullptr if no such view exists. Note that the active view
   // cannot have a |TextInputState.type| of ui::TEXT_INPUT_TYPE_NONE.
   RenderWidgetHostViewBase* active_view_;
 
+  // The following maps track corresponding IME state for views. For each view,
+  // the values in the map are initialized and cleared in Register and
+  // Unregister methods, respectively.
   ViewMap<TextInputState> text_input_state_map_;
-
-  // Text selection bounds information for registered views.
   ViewMap<SelectionRegion> selection_region_map_;
   ViewMap<CompositionRangeInfo> composition_range_info_map_;
 
   base::ObserverList<Observer> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(TextInputManager);
 };
 }
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_TEXT_INPUT_MANAGER_H__