Deprecate Shift+Alt to switch IME and use Ctrl+Shift+Space instead.

ash/accelerators/accelerator_controller.cc

Index: ash/accelerators/accelerator_controller.cc
diff --git a/ash/accelerators/accelerator_controller.cc b/ash/accelerators/accelerator_controller.cc
index b18d0a01a1af496ea7a3b0be59fe3279badddfaa..3c37e993f6b9859dbd4ce3abb4c888753581bf5e 100644
--- a/ash/accelerators/accelerator_controller.cc
+++ b/ash/accelerators/accelerator_controller.cc
@@ -253,33 +253,38 @@ void HandleNewWindow() {
 }
 
 bool CanHandleNextIme(ImeControlDelegate* ime_control_delegate,
-                      const ui::Accelerator& previous_accelerator) {
-  // We only allow next IME to be triggered if the previous is accelerator key
-  // is ONLY either Shift, Alt, Enter or Space.
-  // The first two cases to avoid conflicting accelerators that contain
-  // Alt+Shift (like Alt+Shift+Tab or Alt+Shift+S) to trigger next IME when the
-  // wrong order of key sequences is pressed. crbug.com/527154.
-  // The latter two cases are needed for CJK IME users who tend to press Enter
-  // (or Space) and Shift+Alt almost at the same time to commit an IME string
-  // and then switch from the IME to the English layout. This allows these users
-  // to trigger NEXT_IME even if they press Shift+Alt before releasing Enter.
-  // crbug.com/139556.
-  // TODO(nona|mazda): Fix crbug.com/139556 in a cleaner way.
-  const ui::KeyboardCode previous_key_code = previous_accelerator.key_code();
-  switch (previous_key_code) {
-    case ui::VKEY_SHIFT:
-    case ui::VKEY_LSHIFT:
-    case ui::VKEY_RSHIFT:
-    case ui::VKEY_MENU:
-    case ui::VKEY_LMENU:
-    case ui::VKEY_RMENU:
-    case ui::VKEY_RETURN:
-    case ui::VKEY_SPACE:
-      return ime_control_delegate && ime_control_delegate->CanCycleIme();
-
-    default:
-      return false;
+                      const ui::Accelerator& previous_accelerator,
+                      bool current_accelerator_is_deprecated) {
+  if (current_accelerator_is_deprecated) {
+    // We only allow next IME to be triggered if the previous is accelerator key
+    // is ONLY either Shift, Alt, Enter or Space.
+    // The first six cases below are to avoid conflicting accelerators that
+    // contain Alt+Shift (like Alt+Shift+Tab or Alt+Shift+S) to trigger next IME
+    // when the wrong order of key sequences is pressed. crbug.com/527154.
+    // The latter two cases are needed for CJK IME users who tend to press Enter
+    // (or Space) and Shift+Alt almost at the same time to commit an IME string
+    // and then switch from the IME to the English layout. This allows these
+    // users to trigger NEXT_IME even if they press Shift+Alt before releasing
+    // Enter. crbug.com/139556.
+    // TODO(nona|mazda): Fix crbug.com/139556 in a cleaner way.
+    const ui::KeyboardCode previous_key_code = previous_accelerator.key_code();
+    switch (previous_key_code) {
+      case ui::VKEY_SHIFT:
+      case ui::VKEY_LSHIFT:
+      case ui::VKEY_RSHIFT:
+      case ui::VKEY_MENU:
+      case ui::VKEY_LMENU:
+      case ui::VKEY_RMENU:
+      case ui::VKEY_RETURN:
+      case ui::VKEY_SPACE:
+        break;
+
+      default:
+        return false;
+    }
   }
+
+  return ime_control_delegate && ime_control_delegate->CanCycleIme();
 }
 
 void HandleNextIme(ImeControlDelegate* ime_control_delegate) {
@@ -913,17 +918,19 @@ void AcceleratorController::RegisterAccelerators(
 
 void AcceleratorController::RegisterDeprecatedAccelerators() {
 #if defined(OS_CHROMEOS)
+  for (size_t i = 0; i < kDeprecatedAcceleratorsDataLength; ++i) {
+    const DeprecatedAcceleratorData* data = &kDeprecatedAcceleratorsData[i];
+    actions_with_deprecations_[data->action] = data;
+  }
+
   for (size_t i = 0; i < kDeprecatedAcceleratorsLength; ++i) {
-    const DeprecatedAcceleratorData* data = &kDeprecatedAccelerators[i];
-    const AcceleratorAction action = data->deprecated_accelerator.action;
+    const AcceleratorData& accelerator_data = kDeprecatedAccelerators[i];
     const ui::Accelerator deprecated_accelerator =
-        CreateAccelerator(data->deprecated_accelerator.keycode,
-                          data->deprecated_accelerator.modifiers,
-                          data->deprecated_accelerator.trigger_on_press);
+        CreateAccelerator(accelerator_data.keycode, accelerator_data.modifiers,
+                          accelerator_data.trigger_on_press);
 
     Register(deprecated_accelerator, this);
-    actions_with_deprecations_[action] = data;
-    accelerators_[deprecated_accelerator] = action;
+    accelerators_[deprecated_accelerator] = accelerator_data.action;
     deprecated_accelerators_.insert(deprecated_accelerator);
   }
 #endif  // defined(OS_CHROMEOS)
@@ -964,9 +971,18 @@ bool AcceleratorController::CanPerformAction(
       return CanHandleMagnifyScreen();
     case NEW_INCOGNITO_WINDOW:
       return CanHandleNewIncognitoWindow();
-    case NEXT_IME:
-      return CanHandleNextIme(ime_control_delegate_.get(),
-                              previous_accelerator);
+    case NEXT_IME: {
+#if defined(OS_CHROMEOS)
+      bool accelerator_is_deprecated =
+          (deprecated_accelerators_.count(accelerator) != 0);
+#else
+      // On non-chromeos, the NEXT_IME deprecated accelerators are always used.
+      bool accelerator_is_deprecated = true;
+#endif  // defined(OS_CHROMEOS)
+
+      return CanHandleNextIme(ime_control_delegate_.get(), previous_accelerator,
+                              accelerator_is_deprecated);
+    }
     case PREVIOUS_IME:
       return CanHandlePreviousIme(ime_control_delegate_.get());
     case SCALE_UI_RESET: