Do not hide the web notification popups by the system tray, rather let them avoid (2nd)

ash/system/tray/system_tray.cc

Index: ash/system/tray/system_tray.cc
diff --git a/ash/system/tray/system_tray.cc b/ash/system/tray/system_tray.cc
index dcb034659217e46d01995d606fe166a7599445cf..c93efc96d284f200e22844f9ec87530c72889810 100644
--- a/ash/system/tray/system_tray.cc
+++ b/ash/system/tray/system_tray.cc
@@ -27,6 +27,7 @@
 #include "ash/system/tray_update.h"
 #include "ash/system/user/login_status.h"
 #include "ash/system/user/tray_user.h"
+#include "ash/system/web_notification/web_notification_tray.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/strings/utf_string_conversions.h"
@@ -373,12 +374,13 @@ bool SystemTray::HasSystemBubbleType(SystemTrayBubble::BubbleType type) {
 void SystemTray::DestroySystemBubble() {
   system_bubble_.reset();
   detailed_item_ = NULL;
+  UpdateWebNotifications();
 }
 
 void SystemTray::DestroyNotificationBubble() {
   if (notification_bubble_) {
     notification_bubble_.reset();
-    status_area_widget()->SetHideWebNotifications(false);
+    UpdateWebNotifications();
   }
 }
 
@@ -477,7 +479,8 @@ void SystemTray::ShowItems(const std::vector<SystemTrayItem*>& items,
     detailed_item_ = NULL;
 
   UpdateNotificationBubble();  // State changed, re-create notifications.
-  status_area_widget()->SetHideWebNotifications(true);
+  if (!notification_bubble_)
+    UpdateWebNotifications();
   GetShelfLayoutManager()->UpdateAutoHideState();
 }
 
@@ -527,7 +530,29 @@ void SystemTray::UpdateNotificationBubble() {
   if (hide_notifications_)
     notification_bubble->SetVisible(false);
   else
-    status_area_widget()->SetHideWebNotifications(true);
+    UpdateWebNotifications();
+}
+
+void SystemTray::UpdateWebNotifications() {
+  TrayBubbleView* bubble_view = NULL;
+  if (notification_bubble_)
+    bubble_view = notification_bubble_->bubble_view();
+  else if (system_bubble_)
+    bubble_view = system_bubble_->bubble_view();
+
+  int height = 0;
+  if (bubble_view) {
+    gfx::Rect work_area = Shell::GetScreen()->GetDisplayNearestWindow(
+        bubble_view->GetWidget()->GetNativeView()).work_area();
+    if (GetShelfLayoutManager()->GetAlignment() != SHELF_ALIGNMENT_TOP) {
+      height = std::max(
+          0, work_area.height() - bubble_view->GetBoundsInScreen().y());
+    } else {
+      height = std::max(
+          0, bubble_view->GetBoundsInScreen().bottom() - work_area.y());
+    }
+  }
+  status_area_widget()->web_notification_tray()->SetSystemTrayHeight(height);
 }
 
 void SystemTray::SetShelfAlignment(ShelfAlignment alignment) {