Fix crash when reloading extension with more than one panel open.

chrome/browser/ui/panels/panel_window_controller_cocoa.mm

 // 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 "chrome/browser/ui/panels/panel_window_controller_cocoa.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/logging.h"
 #include "base/mac/mac_util.h"
@@ skipping 120 matching lines @@
   // the renderer the proper size to work with earlier, avoiding a resize
   // after the window is revealed.
   gfx::Rect panelBounds = windowShim_->GetPanelBounds();
   NSRect frame = [window frame];
   frame.size.width = panelBounds.width();
   frame.size.height = panelBounds.height();
   [window setFrame:frame display:NO];
 
   // Attach the RenderWigetHostView to the view hierarchy, it will render
   // HTML content.
-  [[window contentView] addSubview:[self tabContentsView]];
+  NSView* tabContentsView = [self tabContentsView];
+  DCHECK(tabContentsView);
+  [[window contentView] addSubview:tabContentsView];
   [self enableTabContentsViewAutosizing];
 }
 
 - (void)mouseEntered:(NSEvent*)event {
   [titlebar_view_ updateSettingsButtonVisibility:YES];
 }
 
 - (void)mouseExited:(NSEvent*)event {
   [titlebar_view_ updateSettingsButtonVisibility:NO];
 }
 
 - (void)disableTabContentsViewAutosizing {
   NSView* tabContentView = [self tabContentsView];
+  if (!tabContentView)
+    return;
+
   DCHECK([tabContentView superview] == [[self window] contentView]);
   [tabContentView setAutoresizingMask:NSViewNotSizable];
 }
 
 - (void)enableTabContentsViewAutosizing {
   NSView* tabContentView = [self tabContentsView];
+  if (!tabContentView)
+    return;
+
   DCHECK([tabContentView superview] == [[self window] contentView]);
 
   // Parent's bounds is child's frame.
   NSRect frame = [[[self window] contentView] bounds];
   [tabContentView setFrame:frame];
   [tabContentView
       setAutoresizingMask:(NSViewWidthSizable | NSViewHeightSizable)];
 }
 
 - (void)revealAnimatedWithFrame:(const NSRect&)frame {
@@ skipping 69 matching lines @@
   NSView* contentView = [[self window] contentView];
   [contentView addSubview:[findBarCocoaController view]];
 
   CGFloat maxY = NSMaxY([contentView frame]);
   CGFloat maxWidth = NSWidth([contentView frame]);
   [findBarCocoaController positionFindBarViewAtMaxY:maxY maxWidth:maxWidth];
 }
 
 - (NSView*)tabContentsView {
   TabContents* contents = windowShim_->browser()->GetSelectedTabContents();
-  CHECK(contents);
-  NSView* tabContentView = contents->GetNativeView();
-  CHECK(tabContentView);
-  return tabContentView;
+  if (contents)
+    return contents->GetNativeView();
+  return NULL;
 }
 
 - (PanelTitlebarViewCocoa*)titlebarView {
   return titlebar_view_;
 }
 
 // Called to validate menu and toolbar items when this window is key. All the
 // items we care about have been set with the |-commandDispatch:| or
 // |-commandDispatchUsingKeyModifiers:| actions and a target of FirstResponder
 // in IB. If it's not one of those, let it continue up the responder chain to be
@@ skipping 271 matching lines @@
       NotificationService::NoDetails());
 }
 
 // TestingAPI interface implementation
 
 + (void)enableBoundsAnimationNotifications {
   g_reportAnimationStatus = YES;
 }
 
 @end