Reland change for aura tooltips that was revert due to build break:

ui/aura_shell/shell.cc

 // Copyright (c) 2011 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 "ui/aura_shell/shell.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "ui/aura/aura_switches.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/drag_drop_client.h"
 #include "ui/aura/desktop.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_types.h"
 #include "ui/aura_shell/app_list.h"
 #include "ui/aura_shell/default_container_event_filter.h"
 #include "ui/aura_shell/default_container_layout_manager.h"
 #include "ui/aura_shell/desktop_event_filter.h"
 #include "ui/aura_shell/desktop_layout_manager.h"
 #include "ui/aura_shell/drag_drop_controller.h"
 #include "ui/aura_shell/launcher/launcher.h"
 #include "ui/aura_shell/modal_container_layout_manager.h"
 #include "ui/aura_shell/shadow_controller.h"
 #include "ui/aura_shell/shelf_layout_controller.h"
 #include "ui/aura_shell/shell_accelerator_controller.h"
 #include "ui/aura_shell/shell_accelerator_filter.h"
 #include "ui/aura_shell/shell_delegate.h"
 #include "ui/aura_shell/shell_factory.h"
+#include "ui/aura_shell/shell_tooltip_manager.h"
 #include "ui/aura_shell/shell_window_ids.h"
 #include "ui/aura_shell/stacking_controller.h"
 #include "ui/aura_shell/toplevel_layout_manager.h"
 #include "ui/aura_shell/toplevel_window_event_filter.h"
 #include "ui/aura_shell/workspace_controller.h"
 #include "ui/gfx/compositor/layer.h"
 #include "ui/gfx/compositor/layer_animator.h"
 #include "ui/views/widget/native_widget_aura.h"
 #include "ui/views/widget/widget.h"
 
@@ skipping 75 matching lines @@
       delegate_(delegate) {
   aura::Desktop::GetInstance()->SetEventFilter(
       new internal::DesktopEventFilter);
   aura::Desktop::GetInstance()->SetStackingClient(
       new internal::StackingController);
 }
 
 Shell::~Shell() {
   RemoveDesktopEventFilter(accelerator_filter_.get());
 
+  // ShellTooltipManager needs a valid shell instance. We delete it before
+  // deleting the shell |instance_|.
+  RemoveDesktopEventFilter(tooltip_manager_.get());
+  aura::Desktop::GetInstance()->SetProperty(aura::kDesktopTooltipClientKey,
+      NULL);
+  tooltip_manager_.reset();
+
   // Drag drop controller needs a valid shell instance. We destroy it first.
   drag_drop_controller_.reset();
 
   DCHECK(instance_ == this);
   instance_ = NULL;
 
   // Make sure we delete WorkspaceController before launcher is
   // deleted as it has a reference to launcher model.
   workspace_controller_.reset();
 }
@@ skipping 67 matching lines @@
     toplevel_layout_manager->set_shelf(shelf_layout_controller_.get());
   }
 
   // Force a layout.
   desktop_layout->OnWindowResized();
 
   // Initialize ShellAcceleratorFilter
   accelerator_filter_.reset(new internal::ShellAcceleratorFilter);
   AddDesktopEventFilter(accelerator_filter_.get());
 
+  // Initialize ShellTooltipManager
+  tooltip_manager_.reset(new ShellTooltipManager);
+  aura::Desktop::GetInstance()->SetProperty(aura::kDesktopTooltipClientKey,
+      static_cast<aura::TooltipClient*>(tooltip_manager_.get()));
+  AddDesktopEventFilter(tooltip_manager_.get());
+
   // Initialize drag drop controller.
   drag_drop_controller_.reset(new internal::DragDropController);
   aura::Desktop::GetInstance()->SetProperty(aura::kDesktopDragDropClientKey,
       static_cast<aura::DragDropClient*>(drag_drop_controller_.get()));
 }
 
 aura::Window* Shell::GetContainer(int container_id) {
   return const_cast<aura::Window*>(
       const_cast<const aura_shell::Shell*>(this)->GetContainer(container_id));
 }
@@ skipping 34 matching lines @@
       new internal::WorkspaceController(default_container));
   workspace_controller_->SetLauncherModel(launcher_->model());
   default_container->SetEventFilter(
       new internal::DefaultContainerEventFilter(default_container));
   default_container->SetLayoutManager(
       new internal::DefaultContainerLayoutManager(
           workspace_controller_->workspace_manager()));
 }
 
 }  // namespace aura_shell