Use helper DeviceChangeHandler to call mousecontrol/tpcontrol whenever a device is attached.

chrome/browser/chromeos/preferences.cc

Index: chrome/browser/chromeos/preferences.cc
===================================================================
--- chrome/browser/chromeos/preferences.cc	(revision 200880)
+++ chrome/browser/chromeos/preferences.cc	(working copy)
@@ -49,7 +49,8 @@
 }
 
 Preferences::Preferences(input_method::InputMethodManager* input_method_manager)
-    : input_method_manager_(input_method_manager) {
+    : prefs_(NULL),

[xiyuan, 2013/05/21 02:01:44]

Good catch.

+      input_method_manager_(input_method_manager) {
 }
 
 Preferences::~Preferences() {
@@ -525,6 +526,11 @@
   // Initialize preferences to currently saved state.
   NotifyPrefChanged(NULL);
 
+  // Listen to changes in device hierarchy.
+  pointer_device_observer_.reset(new system::PointerDeviceObserver());
+  pointer_device_observer_->AddObserver(this);
+  pointer_device_observer_->Init();
+
   // If a guest is logged in, initialize the prefs as if this is the first
   // login.
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kGuestSession)) {
@@ -544,7 +550,7 @@
   NotifyPrefChanged(&pref_name);
 }
 
-void Preferences::NotifyPrefChanged(const std::string* pref_name) {
+void Preferences::SetTouchpadPrefs(const std::string* pref_name) {
   if (!pref_name || *pref_name == prefs::kTapToClickEnabled) {
     const bool enabled = tap_to_click_enabled_.GetValue();
     system::touchpad_settings::SetTapToClick(enabled);
@@ -584,19 +590,20 @@
     else
       UMA_HISTOGRAM_BOOLEAN("Touchpad.ThreeFingerSwipe.Started", enabled);
   }
-  if (!pref_name || *pref_name == prefs::kNaturalScroll) {
-    // Force natural scroll default if we've sync'd and if the cmd line arg is
-    // set.
-    ForceNaturalScrollDefault();
+  if (!pref_name || *pref_name == prefs::kTouchpadSensitivity) {
+    const int sensitivity = touchpad_sensitivity_.GetValue();
+    system::touchpad_settings::SetSensitivity(sensitivity);
+    if (pref_name) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Touchpad.Sensitivity.Changed", sensitivity, 1, 5, 5);
+    } else {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Touchpad.Sensitivity.Started", sensitivity, 1, 5, 5);
+    }
+  }
+}
 
-    const bool enabled = natural_scroll_.GetValue();
-    DVLOG(1) << "Natural scroll set to " << enabled;
-    ui::SetNaturalScroll(enabled);
-    if (pref_name)
-      UMA_HISTOGRAM_BOOLEAN("Touchpad.NaturalScroll.Changed", enabled);
-    else
-      UMA_HISTOGRAM_BOOLEAN("Touchpad.NaturalScroll.Started", enabled);
-  }
+void Preferences::SetMousePrefs(const std::string* pref_name) {
   if (!pref_name || *pref_name == prefs::kMouseSensitivity) {
     const int sensitivity = mouse_sensitivity_.GetValue();
     system::mouse_settings::SetSensitivity(sensitivity);
@@ -608,17 +615,6 @@
           "Mouse.Sensitivity.Started", sensitivity, 1, 5, 5);
     }
   }
-  if (!pref_name || *pref_name == prefs::kTouchpadSensitivity) {
-    const int sensitivity = touchpad_sensitivity_.GetValue();
-    system::touchpad_settings::SetSensitivity(sensitivity);
-    if (pref_name) {
-      UMA_HISTOGRAM_CUSTOM_COUNTS(
-          "Touchpad.Sensitivity.Changed", sensitivity, 1, 5, 5);
-    } else {
-      UMA_HISTOGRAM_CUSTOM_COUNTS(
-          "Touchpad.Sensitivity.Started", sensitivity, 1, 5, 5);
-    }
-  }
   if (!pref_name || *pref_name == prefs::kPrimaryMouseButtonRight) {
     const bool right = primary_mouse_button_right_.GetValue();
     system::mouse_settings::SetPrimaryButtonRight(right);
@@ -634,6 +630,25 @@
         prefs->SetBoolean(prefs::kOwnerPrimaryMouseButtonRight, right);
     }
   }
+}
+
+void Preferences::NotifyPrefChanged(const std::string* pref_name) {
+  SetTouchpadPrefs(pref_name);
+  SetMousePrefs(pref_name);
+
+  if (!pref_name || *pref_name == prefs::kNaturalScroll) {
+    // Force natural scroll default if we've sync'd and if the cmd line arg is
+    // set.
+    ForceNaturalScrollDefault();
+
+    const bool enabled = natural_scroll_.GetValue();
+    DVLOG(1) << "Natural scroll set to " << enabled;
+    ui::SetNaturalScroll(enabled);
+    if (pref_name)
+      UMA_HISTOGRAM_BOOLEAN("Touchpad.NaturalScroll.Changed", enabled);
+    else
+      UMA_HISTOGRAM_BOOLEAN("Touchpad.NaturalScroll.Started", enabled);
+  }
   if (!pref_name || *pref_name == prefs::kDownloadDefaultDirectory) {
     const base::FilePath pref_path = download_default_directory_.GetValue();
     // TODO(haruki): Remove this when migration completes. crbug.com/229304.
@@ -889,6 +904,14 @@
   }
 }
 
+void Preferences::TouchpadExists(bool exists) {
+  SetTouchpadPrefs(NULL);
+}
+
+void Preferences::MouseExists(bool exists) {
+  SetMousePrefs(NULL);
+}
+
 void Preferences::SetLanguageConfigBoolean(const char* section,
                                            const char* name,
                                            bool value) {