Disable delegation to picker controller once it is deleted.

chrome/browser/ui/cocoa/web_intent_picker_cocoa.mm

Index: chrome/browser/ui/cocoa/web_intent_picker_cocoa.mm
diff --git a/chrome/browser/ui/cocoa/web_intent_picker_cocoa.mm b/chrome/browser/ui/cocoa/web_intent_picker_cocoa.mm
index b563a2e7f6cc453fa844cff2c273c1c665162bf6..f1a45c6dc79a6a21dd0a2777c75c8c87761540e0 100644
--- a/chrome/browser/ui/cocoa/web_intent_picker_cocoa.mm
+++ b/chrome/browser/ui/cocoa/web_intent_picker_cocoa.mm
@@ -120,7 +120,8 @@ void WebIntentPickerCocoa::OnSheetDidEnd(NSWindow* sheet) {
   [sheet orderOut:sheet_controller_];
   if (window_)
     window_->CloseConstrainedWindow();
-  delegate_->OnClosing();
+  if (delegate_)
+    delegate_->OnClosing();
 }
 
 void WebIntentPickerCocoa::Close() {
@@ -164,7 +165,7 @@ void WebIntentPickerCocoa::OnExtensionIconChanged(
 
 void WebIntentPickerCocoa::OnInlineDisposition(const string16& title,
                                                const GURL& url) {
-
+  DCHECK(delegate_);
   content::WebContents* web_contents =
       delegate_->CreateWebContentsForInlineDisposition(
           tab_contents_->profile(), url);
@@ -207,6 +208,7 @@ void WebIntentPickerCocoa::OnServiceChosen(size_t index) {
 
 void WebIntentPickerCocoa::OnExtensionInstallRequested(
     const std::string& extension_id) {
+  DCHECK(delegate_);
   delegate_->OnExtensionInstallRequested(extension_id);
 }
 
@@ -231,6 +233,10 @@ void WebIntentPickerCocoa::OnInlineDispositionAutoResize(
 void WebIntentPickerCocoa::OnPendingAsyncCompleted() {
 }
 
+void WebIntentPickerCocoa::InvalidateDelegate() {
+  delegate_ = NULL;
+}
+
 void WebIntentPickerCocoa::OnExtensionLinkClicked(
     const std::string& id,
     WindowOpenDisposition disposition) {