[Panels] Fix browser crash when killing extension on Windows.

chrome/browser/ui/panels/panel_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.
 
 #include "chrome/browser/ui/panels/panel_view.h"
 
 #include <map>
 #include "base/logging.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/app/chrome_command_ids.h"
@@ skipping 268 matching lines @@
   panel_->manager()->OnPanelAnimationEnded(panel_.get());
 }
 
 void PanelView::AnimationProgressed(const ui::Animation* animation) {
   gfx::Rect new_bounds = bounds_animator_->CurrentValueBetween(
       animation_start_bounds_, bounds_);
   GetWidget()->SetBounds(new_bounds);
 }
 
 void PanelView::ClosePanel() {
+  // We're already closing. Do nothing.
+  if (!window_)
+    return;
+
+  if (!panel_->ShouldCloseWindow())
+    return;
+
   // Cancel any currently running animation since we're closing down.
   if (bounds_animator_.get())
     bounds_animator_.reset();
 
+  if (panel_->GetWebContents()) {
+    // Still have web contents. Allow renderer to shut down.
+    // When web contents are destroyed, we will be called back again.
+    panel_->OnWindowClosing();
+    return;
+  }
+
   panel_->OnNativePanelClosed();
   window_->Close();
+  window_ = NULL;
 }
 
 void PanelView::ActivatePanel() {
   window_->Activate();
 }
 
 void PanelView::DeactivatePanel() {
   window_->Deactivate();
 }
 
@@ skipping 452 matching lines @@
   int height = web_view_->size().height();
   SkRegion* region = new SkRegion;
   region->op(0, 0, kResizeInsideBoundsSize, height, SkRegion::kUnion_Op);
   region->op(width - kResizeInsideBoundsSize, 0, width, height,
       SkRegion::kUnion_Op);
   region->op(0, height - kResizeInsideBoundsSize, width, height,
       SkRegion::kUnion_Op);
   web_contents->GetRenderViewHost()->GetView()->SetClickthroughRegion(region);
 #endif
 }