Reduce CPU usage for input method switching.

- Move GetNumActiveInputMethods call from input_method_menu_button.cc to input_method_library.cc so that the IBus function is called only once even when multiple Chrome windows are available.
- Improved InputMethodMenu::InputMethodChanged so that only the first input method button would update Preferences.
- Remove ImePropertiesChanged callback. It's obsolete.

BUG=chromium-os:8553
TEST=manually.

Review URL: http://codereview.chromium.org/4162002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@67973 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 117 insertions, 46 deletions

diff --git a/chrome/browser/chromeos/cros/input_method_library.cc b/chrome/browser/chromeos/cros/input_method_library.cc
index 1e6f15a..9b5316f 100644
--- a/chrome/browser/chromeos/cros/input_method_library.cc
+++ b/chrome/browser/chromeos/cros/input_method_library.cc
@@ -23,6 +23,7 @@
 #include "chrome/common/notification_service.h"
 
 namespace {
+
 const char kIBusDaemonPath[] = "/usr/bin/ibus-daemon";
 const char kCandidateWindowPath[] = "/opt/google/chrome/candidate_window";
 
@@ -290,7 +291,11 @@ class InputMethodLibraryImpl : public InputMethodLibrary,
     }
 
     if (active_input_methods_are_changed) {
-      FOR_EACH_OBSERVER(Observer, observers_, ActiveInputMethodsChanged(this));
+      const size_t num_active_input_methods = GetNumActiveInputMethods();
+      FOR_EACH_OBSERVER(Observer, observers_,
+                        ActiveInputMethodsChanged(this,
+                                                  current_input_method_,
+                                                  num_active_input_methods));
     }
   }
 
@@ -386,13 +391,29 @@ class InputMethodLibraryImpl : public InputMethodLibrary,
       previous_input_method_ = current_input_method_;
       current_input_method_ = new_input_method;
     }
-    FOR_EACH_OBSERVER(Observer, observers_, InputMethodChanged(this));
+    const size_t num_active_input_methods = GetNumActiveInputMethods();
+    FOR_EACH_OBSERVER(Observer, observers_,
+                      InputMethodChanged(this,
+                                         previous_input_method_,
+                                         current_input_method_,
+                                         num_active_input_methods));
+
+    // Ask the first observer to update preferences. We should not ask every
+    // observer to do so. Otherwise, we'll end up updating preferences many
+    // times when many observers are attached (ex. many windows are opened),
+    // which is unnecessary and expensive.
+    ObserverListBase<Observer>::Iterator it(observers_);
+    Observer* first_observer = it.GetNext();
+    if (first_observer) {
+      first_observer->PreferenceUpdateNeeded(this,
+                                             previous_input_method_,
+                                             current_input_method_);
+    }
   }
 
   void RegisterProperties(const ImePropertyList& prop_list) {
     // |prop_list| might be empty. This means "clear all properties."
     current_ime_properties_ = prop_list;
-    FOR_EACH_OBSERVER(Observer, observers_, ImePropertiesChanged(this));
   }
 
   void StartInputMethodProcesses() {
@@ -404,7 +425,6 @@ class InputMethodLibraryImpl : public InputMethodLibrary,
     for (size_t i = 0; i < prop_list.size(); ++i) {
       FindAndUpdateProperty(prop_list[i], &current_ime_properties_);
     }
-    FOR_EACH_OBSERVER(Observer, observers_, ImePropertiesChanged(this));
   }
 
   // Launches an input method procsess specified by the given command
diff --git a/chrome/browser/chromeos/cros/input_method_library.h b/chrome/browser/chromeos/cros/input_method_library.h
index f3bbe3c..7f55eea 100644
--- a/chrome/browser/chromeos/cros/input_method_library.h
+++ b/chrome/browser/chromeos/cros/input_method_library.h
@@ -26,14 +26,23 @@ class InputMethodLibrary {
    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() {}
 
diff --git a/chrome/browser/chromeos/login/keyboard_switch_menu.cc b/chrome/browser/chromeos/login/keyboard_switch_menu.cc
index de2026b..ff11bee 100644
--- a/chrome/browser/chromeos/login/keyboard_switch_menu.cc
+++ b/chrome/browser/chromeos/login/keyboard_switch_menu.cc
@@ -24,8 +24,10 @@ KeyboardSwitchMenu::KeyboardSwitchMenu()
 
 ////////////////////////////////////////////////////////////////////////////////
 // InputMethodMenu::InputMethodMenuHost implementation.
-void KeyboardSwitchMenu::UpdateUI(
-    const std::wstring& name, const std::wstring& tooltip) {
+void KeyboardSwitchMenu::UpdateUI(const std::string& input_method_id,
+                                  const std::wstring& name,
+                                  const std::wstring& tooltip,
+                                  size_t num_active_input_methods) {
   // Update all view hierarchies so that the new input method name is shown in
   // the menu button.
   views::Widget::NotifyLocaleChanged();
diff --git a/chrome/browser/chromeos/login/keyboard_switch_menu.h b/chrome/browser/chromeos/login/keyboard_switch_menu.h
index 64bd2aa..48c0982 100644
--- a/chrome/browser/chromeos/login/keyboard_switch_menu.h
+++ b/chrome/browser/chromeos/login/keyboard_switch_menu.h
@@ -23,8 +23,10 @@ class KeyboardSwitchMenu : public InputMethodMenu {
   virtual ~KeyboardSwitchMenu() {}
 
   // InputMethodMenu::InputMethodMenuHost implementation.
-  virtual void UpdateUI(
-      const std::wstring& name, const std::wstring& tooltip);
+  virtual void UpdateUI(const std::string& input_method_id,
+                        const std::wstring& name,
+                        const std::wstring& tooltip,
+                        size_t num_active_input_methods);
   virtual bool ShouldSupportConfigUI() { return false; }
   virtual void OpenConfigUI() {}
 
diff --git a/chrome/browser/chromeos/status/input_method_menu.cc b/chrome/browser/chromeos/status/input_method_menu.cc
index 027f141..8260e087 100644
--- a/chrome/browser/chromeos/status/input_method_menu.cc
+++ b/chrome/browser/chromeos/status/input_method_menu.cc
@@ -378,16 +378,20 @@ void InputMethodMenu::RunMenu(
 ////////////////////////////////////////////////////////////////////////////////
 // InputMethodLibrary::Observer implementation:
 
-void InputMethodMenu::InputMethodChanged(InputMethodLibrary* obj) {
+void InputMethodMenu::InputMethodChanged(
+    InputMethodLibrary* obj,
+    const InputMethodDescriptor& previous_input_method,
+    const InputMethodDescriptor& current_input_method,
+    size_t num_active_input_methods) {
   UserMetrics::RecordAction(
       UserMetricsAction("LanguageMenuButton_InputMethodChanged"));
+  UpdateUIFromInputMethod(current_input_method, num_active_input_methods);
+}
 
-  const InputMethodDescriptor& previous_input_method =
-      obj->previous_input_method();
-  const InputMethodDescriptor& current_input_method =
-      obj->current_input_method();
-  UpdateUIFromInputMethod(current_input_method);
-  // Update Chrome prefs as well.
+void InputMethodMenu::PreferenceUpdateNeeded(
+    InputMethodLibrary* obj,
+    const InputMethodDescriptor& previous_input_method,
+    const InputMethodDescriptor& current_input_method) {
   if (is_browser_mode_) {
     if (pref_service_) {  // make sure we're not in unit tests.
       // Sometimes (e.g. initial boot) |previous_input_method.id| is empty.
@@ -418,20 +422,21 @@ void InputMethodMenu::PrepareForMenuOpen() {
   }
 }
 
-void InputMethodMenu::ActiveInputMethodsChanged(InputMethodLibrary* obj) {
+void InputMethodMenu::ActiveInputMethodsChanged(
+    InputMethodLibrary* obj,
+    const InputMethodDescriptor& current_input_method,
+    size_t num_active_input_methods) {
   // Update the icon if active input methods are changed. See also
-  // comments in UpdateUI()
-  UpdateUIFromInputMethod(obj->current_input_method());
-}
-
-void InputMethodMenu::ImePropertiesChanged(InputMethodLibrary* obj) {
+  // comments in UpdateUI() in input_method_menu_button.cc.
+  UpdateUIFromInputMethod(current_input_method, num_active_input_methods);
 }
 
 void InputMethodMenu::UpdateUIFromInputMethod(
-    const InputMethodDescriptor& input_method) {
+    const InputMethodDescriptor& input_method,
+    size_t num_active_input_methods) {
   const std::wstring name = GetTextForIndicator(input_method);
   const std::wstring tooltip = GetTextForMenu(input_method);
-  UpdateUI(name, tooltip);
+  UpdateUI(input_method.id, name, tooltip, num_active_input_methods);
 }
 
 void InputMethodMenu::RebuildModel() {
diff --git a/chrome/browser/chromeos/status/input_method_menu.h b/chrome/browser/chromeos/status/input_method_menu.h
index a132c87..a25ee36 100644
--- a/chrome/browser/chromeos/status/input_method_menu.h
+++ b/chrome/browser/chromeos/status/input_method_menu.h
@@ -63,9 +63,19 @@ class InputMethodMenu : public views::ViewMenuDelegate,
                        const gfx::Point& pt);
 
   // InputMethodLibrary::Observer implementation.
-  virtual void InputMethodChanged(InputMethodLibrary* obj);
-  virtual void ImePropertiesChanged(InputMethodLibrary* obj);
-  virtual void ActiveInputMethodsChanged(InputMethodLibrary* obj);
+  virtual void InputMethodChanged(
+      InputMethodLibrary* obj,
+      const InputMethodDescriptor& previous_input_method,
+      const InputMethodDescriptor& current_input_method,
+      size_t num_active_input_methods);
+  virtual void ActiveInputMethodsChanged(
+      InputMethodLibrary* obj,
+      const InputMethodDescriptor& current_input_method,
+      size_t num_active_input_methods);
+  virtual void PreferenceUpdateNeeded(
+    InputMethodLibrary* obj,
+    const InputMethodDescriptor& previous_input_method,
+    const InputMethodDescriptor& current_input_method);
 
   // NotificationObserver implementation.
   virtual void Observe(NotificationType type,
@@ -89,7 +99,8 @@ class InputMethodMenu : public views::ViewMenuDelegate,
 
  protected:
   // Parses |input_method| and then calls UpdateUI().
-  void UpdateUIFromInputMethod(const InputMethodDescriptor& input_method);
+  void UpdateUIFromInputMethod(const InputMethodDescriptor& input_method,
+                               size_t num_active_input_methods);
 
   // Rebuilds model and menu2 objects in preparetion to open the menu.
   void PrepareForMenuOpen();
@@ -102,8 +113,10 @@ class InputMethodMenu : public views::ViewMenuDelegate,
  private:
   // Updates UI of a container of the menu (e.g. the "US" menu button in the
   // status area). Sub classes have to implement the interface for their own UI.
-  virtual void UpdateUI(
-      const std::wstring& name, const std::wstring& tooltip) = 0;
+  virtual void UpdateUI(const std::string& input_method_id,  // e.g. "mozc"
+                        const std::wstring& name,  // e.g. "US", "INTL"
+                        const std::wstring& tooltip,
+                        size_t num_active_input_methods) = 0;
 
   // Sub classes have to implement the interface. This interface should return
   // true if the dropdown menu should show an item like "Customize languages
diff --git a/chrome/browser/chromeos/status/input_method_menu_button.cc b/chrome/browser/chromeos/status/input_method_menu_button.cc
index 1fb5fa2..bc714bc 100644
--- a/chrome/browser/chromeos/status/input_method_menu_button.cc
+++ b/chrome/browser/chromeos/status/input_method_menu_button.cc
@@ -7,6 +7,7 @@
 #include <string>
 
 #include "app/resource_bundle.h"
+#include "base/utf_string_conversions.h"
 #include "chrome/browser/chromeos/cros/cros_library.h"
 #include "chrome/browser/chromeos/cros/keyboard_library.h"
 #include "chrome/browser/chromeos/input_method/input_method_util.h"
@@ -54,11 +55,16 @@ InputMethodMenuButton::InputMethodMenuButton(StatusAreaHost* host)
   SetShowMultipleIconStates(false);
   set_alignment(TextButton::ALIGN_CENTER);
 
+  chromeos::KeyboardLibrary* keyboard_library =
+      chromeos::CrosLibrary::Get()->GetKeyboardLibrary();
+  const std::string hardware_keyboard_id =  // e.g. "xkb:us::eng"
+      keyboard_library->GetHardwareKeyboardLayoutName();
+
   // Draw the default indicator "US". The default indicator "US" is used when
   // |pref_service| is not available (for example, unit tests) or |pref_service|
   // is available, but Chrome preferences are not available (for example,
   // initial OS boot).
-  InputMethodMenuButton::UpdateUI(L"US", L"");
+  InputMethodMenuButton::UpdateUI(hardware_keyboard_id, L"US", L"", 1);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -74,9 +80,21 @@ gfx::Size InputMethodMenuButton::GetPreferredSize() {
 
 void InputMethodMenuButton::OnLocaleChanged() {
   input_method::OnLocaleChanged();
+
+  chromeos::InputMethodLibrary* input_method_library =
+      chromeos::CrosLibrary::Get()->GetInputMethodLibrary();
   const InputMethodDescriptor& input_method =
-      CrosLibrary::Get()->GetInputMethodLibrary()->current_input_method();
-  UpdateUIFromInputMethod(input_method);
+      input_method_library->current_input_method();
+
+  // In general, we should not call an input method API in the input method
+  // button classes (status/input_menu_button*.cc) for performance reasons (see
+  // http://crosbug.com/8284). However, since OnLocaleChanged is called only in
+  // OOBE/Login screen which does not have two or more Chrome windows, it's okay
+  // to call GetNumActiveInputMethods here.
+  const size_t num_active_input_methods =
+      input_method_library->GetNumActiveInputMethods();
+
+  UpdateUIFromInputMethod(input_method, num_active_input_methods);
   Layout();
   SchedulePaint();
 }
@@ -84,16 +102,16 @@ void InputMethodMenuButton::OnLocaleChanged() {
 ////////////////////////////////////////////////////////////////////////////////
 // InputMethodMenu::InputMethodMenuHost implementation:
 
-void InputMethodMenuButton::UpdateUI(
-    const std::wstring& name, const std::wstring& tooltip) {
+void InputMethodMenuButton::UpdateUI(const std::string& input_method_id,
+                                     const std::wstring& name,
+                                     const std::wstring& tooltip,
+                                     size_t num_active_input_methods) {
   // Hide the button only if there is only one input method, and the input
   // method is a XKB keyboard layout. We don't hide the button for other
   // types of input methods as these might have intra input method modes,
   // like Hiragana and Katakana modes in Japanese input methods.
-  scoped_ptr<InputMethodDescriptors> active_input_methods(
-      CrosLibrary::Get()->GetInputMethodLibrary()->GetActiveInputMethods());
-  if (active_input_methods->size() == 1 &&
-      input_method::IsKeyboardLayout(active_input_methods->at(0).id) &&
+  if (num_active_input_methods == 1 &&
+      input_method::IsKeyboardLayout(input_method_id) &&
       host_->IsBrowserMode()) {
     // As the disabled color is set to invisible, disabling makes the
     // button disappear.
diff --git a/chrome/browser/chromeos/status/input_method_menu_button.h b/chrome/browser/chromeos/status/input_method_menu_button.h
index d7375d3..3a232eb 100644
--- a/chrome/browser/chromeos/status/input_method_menu_button.h
+++ b/chrome/browser/chromeos/status/input_method_menu_button.h
@@ -29,8 +29,10 @@ class InputMethodMenuButton : public StatusAreaButton,
 
  private:
   // InputMethodMenu implementation.
-  virtual void UpdateUI(
-      const std::wstring& name, const std::wstring& tooltip);
+  virtual void UpdateUI(const std::string& input_method_id,
+                        const std::wstring& name,
+                        const std::wstring& tooltip,
+                        size_t num_active_input_methods);
   virtual bool ShouldSupportConfigUI();
   virtual void OpenConfigUI();