Revise the shelf alignment locking mechanism.

ash/system/web_notification/web_notification_tray.cc

 // 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.
 
 #include "ash/system/web_notification/web_notification_tray.h"
 
 #include "ash/ash_switches.h"
 #include "ash/root_window_controller.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shelf/shelf_layout_manager_observer.h"
+#include "ash/shelf/shelf_util.h"
 #include "ash/shelf/shelf_widget.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/system/status_area_widget.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/tray/tray_background_view.h"
 #include "ash/system/tray/tray_bubble_wrapper.h"
 #include "ash/system/tray/tray_constants.h"
 #include "ash/system/tray/tray_utils.h"
 #include "ash/system/web_notification/ash_popup_alignment_delegate.h"
@@ skipping 190 matching lines @@
   if (!ShouldShowMessageCenter())
     return false;
 
   should_block_shelf_auto_hide_ = true;
   message_center::MessageCenterBubble* message_center_bubble =
       new message_center::MessageCenterBubble(
           message_center(),
           message_center_tray_.get(),
           true);
 
-  int max_height = 0;
+  // Assume the status area and bubble bottoms are aligned when vertical.
   aura::Window* status_area_window = status_area_widget()->GetNativeView();
-  switch (GetShelfLayoutManager()->GetAlignment()) {
-    case SHELF_ALIGNMENT_BOTTOM: {
-      gfx::Rect shelf_bounds = GetShelfLayoutManager()->GetIdealBounds();
-      max_height = shelf_bounds.y();
-      break;
-    }
-    case SHELF_ALIGNMENT_LEFT:
-    case SHELF_ALIGNMENT_RIGHT: {
-      // Assume that the bottom line of the status area widget and the bubble
-      // are aligned.
-      max_height = status_area_window->GetBoundsInRootWindow().bottom();
-      break;
-    }
-  }
+  const int max_height =
+      IsHorizontalAlignment(GetShelfLayoutManager()->GetAlignment())
+          ? GetShelfLayoutManager()->GetIdealBounds().y()
+          : status_area_window->GetBoundsInRootWindow().bottom();
 
-  message_center_bubble->SetMaxHeight(std::max(0,
-                                               max_height - kTraySpacing));
+  message_center_bubble->SetMaxHeight(std::max(0, max_height - kTraySpacing));
   if (show_settings)
     message_center_bubble->SetSettingsVisible();
   message_center_bubble_.reset(
       new WebNotificationBubbleWrapper(this, message_center_bubble));
 
   status_area_widget()->SetHideSystemNotifications(true);
   GetShelfLayoutManager()->UpdateAutoHideState();
   button_->SetBubbleVisible(true);
   SetDrawBackgroundAsActive(true);
   return true;
@@ skipping 238 matching lines @@
 
 message_center::MessageCenterBubble*
 WebNotificationTray::GetMessageCenterBubbleForTest() {
   if (!message_center_bubble())
     return NULL;
   return static_cast<message_center::MessageCenterBubble*>(
       message_center_bubble()->bubble());
 }
 
 }  // namespace ash