Magnifier needs to follow the focus of the textfield.

ui/base/ime/input_method_base.h

 // Copyright (c) 2012 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 UI_BASE_IME_INPUT_METHOD_BASE_H_
 #define UI_BASE_IME_INPUT_METHOD_BASE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 63 matching lines @@
   // input type is not TEXT_INPUT_TYPE_NONE.
   void OnInputMethodChanged() const;
 
   // Convenience method to call delegate_->DispatchKeyEventPostIME().
   // Returns true if the event was processed
   bool DispatchKeyEventPostIME(const ui::KeyEvent& event) const;
 
   // Convenience method to notify all observers of TextInputClient changes.
   void NotifyTextInputStateChanged(const TextInputClient* client);
 
+  void NotifyTextInputCaretBoundsChanged(const TextInputClient* client);
+
   // Interface for for signalling candidate window events.
   // See also *Callback functions below. To avoid reentrancy issue that
   // TextInputClient manipulates IME state during even handling, these methods
   // defer sending actual signals to renderer.
   void OnCandidateWindowShown();
   void OnCandidateWindowUpdated();
   void OnCandidateWindowHidden();
 
   bool system_toplevel_window_focused() const {
     return system_toplevel_window_focused_;
@@ skipping 14 matching lines @@
   ObserverList<InputMethodObserver> observer_list_;
 
   bool system_toplevel_window_focused_;
 
   DISALLOW_COPY_AND_ASSIGN(InputMethodBase);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_IME_INPUT_METHOD_BASE_H_