Reduce CPU usage for input method switching.

chrome/browser/chromeos/cros/input_method_library.h

 // Copyright (c) 2010 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 CHROME_BROWSER_CHROMEOS_CROS_INPUT_METHOD_LIBRARY_H_
 #define CHROME_BROWSER_CHROMEOS_CROS_INPUT_METHOD_LIBRARY_H_
 #pragma once
 
 #include <string>
 #include <utility>
 
 #include "base/observer_list.h"
 #include "base/time.h"
 #include "base/timer.h"
 #include "cros/chromeos_input_method.h"
 
 namespace chromeos {
 
 // This class handles the interaction with the ChromeOS language library APIs.
 // Classes can add themselves as observers. Users can get an instance of this
 // library class like this:
 //   chromeos::CrosLibrary::Get()->GetInputMethodLibrary()
 class InputMethodLibrary {
  public:
   class Observer {
    public:
     virtual ~Observer() = 0;
     // Called when the current input method is changed.
-    virtual void InputMethodChanged(InputMethodLibrary* obj) = 0;
-
-    // Called when input method properties (see chromeos_input_method.h
-    // for details) are changed.
-    virtual void ImePropertiesChanged(InputMethodLibrary* obj) = 0;
+    virtual void InputMethodChanged(
+        InputMethodLibrary* obj,
+        const InputMethodDescriptor& previous_input_method,
+        const InputMethodDescriptor& current_input_method,
+        size_t num_active_input_methods) = 0;
 
     // Called when the active input methods are changed.
-    virtual void ActiveInputMethodsChanged(InputMethodLibrary* obj) = 0;
+    virtual void ActiveInputMethodsChanged(
+        InputMethodLibrary* obj,
+        const InputMethodDescriptor& current_input_method,
+        size_t num_active_input_methods) = 0;
+
+    // Called when the preferences have to be updated.
+    virtual void PreferenceUpdateNeeded(
+        InputMethodLibrary* obj,
+        const InputMethodDescriptor& previous_input_method,
+        const InputMethodDescriptor& current_input_method) = 0;
   };
   virtual ~InputMethodLibrary() {}
 
   // Adds an observer to receive notifications of input method related
   // changes as desribed in the Observer class above.
   virtual void AddObserver(Observer* observer) = 0;
   virtual void RemoveObserver(Observer* observer) = 0;
 
   // Returns the list of input methods we can select (i.e. active). If the cros
   // library is not found or IBus/DBus daemon is not alive, this function
@@ skipping 66 matching lines @@
   virtual const ImePropertyList& current_ime_properties() const = 0;
 
   // Factory function, creates a new instance and returns ownership.
   // For normal usage, access the singleton via CrosLibrary::Get().
   static InputMethodLibrary* GetImpl(bool stub);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_CROS_INPUT_METHOD_LIBRARY_H_