linux_aura: Fix crash on drags from the omnibox.

ui/views/view.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.
 
 #define _USE_MATH_DEFINES // For VC++ to get M_PI. This has to be first.
 
 #include "ui/views/view.h"
 
 #include <algorithm>
 #include <cmath>
 
+#include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "third_party/skia/include/core/SkRect.h"
 #include "ui/base/accessibility/accessibility_types.h"
 #include "ui/base/dragdrop/drag_drop_types.h"
 #include "ui/base/ui_base_switches_util.h"
@@ skipping 156 matching lines @@
       paint_to_layer_(false),
       accelerator_registration_delayed_(false),
       accelerator_focus_manager_(NULL),
       registered_accelerator_count_(0),
       next_focusable_view_(NULL),
       previous_focusable_view_(NULL),
       focusable_(false),
       accessibility_focusable_(false),
       context_menu_controller_(NULL),
       drag_controller_(NULL),
+      currently_dragging_(false),
       post_dispatch_handler_(new internal::PostEventDispatchHandler(this)),
       native_view_accessibility_(NULL) {
   AddPostTargetHandler(post_dispatch_handler_.get());
 }
 
 View::~View() {
   if (parent_)
     parent_->RemoveChildView(this);
 
+  // If we destroy the view during a drag, AutoReset will probably write to
+  // freed memory.
+  DCHECK(!currently_dragging_);
+
   for (Views::const_iterator i(children_.begin()); i != children_.end(); ++i) {
     (*i)->parent_ = NULL;
     if (!(*i)->owned_by_client_)
       delete *i;
   }
 
   // Release ownership of the native accessibility object, but it's
   // reference-counted on some platforms, so it may not be deleted right away.
   if (native_view_accessibility_)
     native_view_accessibility_->Destroy();
@@ skipping 2104 matching lines @@
   if (widget && widget->native_widget_private()->GetTooltipManager())
     widget->native_widget_private()->GetTooltipManager()->UpdateTooltip();
 }
 
 // Drag and drop ---------------------------------------------------------------
 
 bool View::DoDrag(const ui::LocatedEvent& event,
                   const gfx::Point& press_pt,
                   ui::DragDropTypes::DragEventSource source) {
 #if !defined(OS_MACOSX)
+  if (currently_dragging_)
+    return false;
+
   int drag_operations = GetDragOperations(press_pt);
   if (drag_operations == ui::DragDropTypes::DRAG_NONE)
     return false;
 
+  base::AutoReset<bool> updating_focus(&currently_dragging_, true);
   OSExchangeData data;
   WriteDragData(press_pt, &data);
 
   // Message the RootView to do the drag and drop. That way if we're removed
   // the RootView can detect it and avoid calling us back.
   gfx::Point widget_location(event.location());
   ConvertPointToWidget(this, &widget_location);
   GetWidget()->RunShellDrag(this, data, widget_location, drag_operations,
       source);
+
   return true;
 #else
   return false;
 #endif  // !defined(OS_MACOSX)
 }
 
 }  // namespace views