linux_aura: Fix cursor memeory leak, which was redding the lsan bot.

ui/views/widget/desktop_aura/desktop_native_widget_aura.cc

Index: ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
diff --git a/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc b/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
index 37da13a326cb77550cf604e03d19f9f90330be26..2c4f085143092bf4517d226f06b3c13d6aa9b762 100644
--- a/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
+++ b/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
@@ -210,6 +210,7 @@ class FocusManagerEventHandler : public ui::EventHandler {
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopNativeWidgetAura, public:
 
+int DesktopNativeWidgetAura::cursor_reference_count_ = 0;
 DesktopNativeCursorManager* DesktopNativeWidgetAura::native_cursor_manager_ =
     NULL;
 views::corewm::CursorManager* DesktopNativeWidgetAura::cursor_manager_ = NULL;
@@ -301,6 +302,15 @@ void DesktopNativeWidgetAura::OnDesktopWindowTreeHostDestroyed(
   aura::client::SetCursorClient(root->window(), NULL);
   native_cursor_manager_->RemoveRootWindow(root);
 
+  cursor_reference_count_--;
+  if (cursor_reference_count_ == 0) {
+    // We are the last DesktopNativeWidgetAura instance, and we are responsible
+    // for cleaning up |cursor_manager_|.
+    delete cursor_manager_;
+    native_cursor_manager_ = NULL;
+    cursor_manager_ = NULL;
+  }

[sadrul, 2014/01/15 22:15:01]

This looks a bit hairy. Perhaps there could be a
[D]CHECK_GE(cursor_reference_count_, 0) here

+
   aura::client::SetScreenPositionClient(root->window(), NULL);
   position_client_.reset();
 
@@ -397,6 +407,7 @@ void DesktopNativeWidgetAura::InitNativeWidget(
 
   // |root_window_| must be added to |native_cursor_manager_| before
   // OnRootWindowCreated() is called.
+  cursor_reference_count_++;
   if (!native_cursor_manager_) {
     native_cursor_manager_ = new DesktopNativeCursorManager(
         DesktopCursorLoaderUpdater::Create());