Attempt at fixing tab dragging crash. I believe the crash is happening

because there is an existing TabDragController when a new one is
created. Right after we create the new TabDragController it replaces
the old, but if we create the new one before the old is destroyed it
means the old is still set as a delegate on the TabContents so that
when the new restores the delegates it restores the old
TabDragController, which has now been deleted.

BUG=107172
TEST=none
R=ben@chromium.org


Review URL: http://codereview.chromium.org/8915026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@114653 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/views/tabs/base_tab_strip.cc

@@ -343,6 +343,10 @@ void BaseTabStrip::MaybeStartDrag(
   TabStripSelectionModel selection_model;
   if (!original_selection.IsSelected(model_index))
     selection_model.Copy(original_selection);
+  // Delete the existing DragController before creating a new one. We do this as
+  // creating the DragController remembers the TabContents delegates and we need
+  // to make sure the existing DragController isn't still a delegate.
+  drag_controller_.reset();
   drag_controller_.reset(TabDragController::Create(
       this, tab, tabs, gfx::Point(x, y), tab->GetMirroredXInView(event.x()),
       selection_model));