Don't leave renderer process frozen when canceling JavaScript dialogs.

chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.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/app_modal_dialogs/javascript_app_modal_dialog.h"
 
 #include "base/command_line.h"
 #include "chrome/browser/browser_shutdown.h"
 #include "chrome/browser/ui/app_modal_dialogs/native_app_modal_dialog.h"
 #include "chrome/common/chrome_switches.h"
@@ skipping 51 matching lines @@
     ExtraDataMap* extra_data_map,
     const string16& title,
     content::JavaScriptMessageType javascript_message_type,
     const string16& message_text,
     const string16& default_prompt_text,
     bool display_suppress_checkbox,
     bool is_before_unload_dialog,
     bool is_reload,
     const JavaScriptDialogManager::DialogClosedCallback& callback)
     : AppModalDialog(web_contents, title),
+      WebContentsObserver(web_contents),
+      render_view_host_(web_contents->GetRenderViewHost()),
       extra_data_map_(extra_data_map),
       javascript_message_type_(javascript_message_type),
       display_suppress_checkbox_(display_suppress_checkbox),
       is_before_unload_dialog_(is_before_unload_dialog),
       is_reload_(is_reload),
       callback_(callback),
       use_override_prompt_text_(false) {
   EnforceMaxTextSize(message_text, &message_text_);
   EnforceMaxPromptSize(default_prompt_text, &default_prompt_text_);
 }
 
 JavaScriptAppModalDialog::~JavaScriptAppModalDialog() {
 }
 
 NativeAppModalDialog* JavaScriptAppModalDialog::CreateNativeDialog() {
   gfx::NativeWindow parent_window =
-      web_contents()->GetView()->GetTopLevelNativeWindow();
+      AppModalDialog::web_contents()->GetView()->GetTopLevelNativeWindow();
 
 #if defined(USE_AURA)
   if (!parent_window->GetRootWindow()) {
     // When we are part of a WebContents that isn't actually being displayed on
     // the screen, we can't actually attach to it.
     parent_window = NULL;
   }
 #endif  // defined(USE_AURA)
 
   return NativeAppModalDialog::CreateNativeJavaScriptPrompt(this,
                                                             parent_window);
 }
 
 bool JavaScriptAppModalDialog::IsJavaScriptModalDialog() {
   return true;
 }
 
 void JavaScriptAppModalDialog::Invalidate() {
   if (!IsValid())
     return;
 
   AppModalDialog::Invalidate();
-  callback_.Reset();
+  if (!callback_.is_null()) {
+    callback_.Run(false, string16());
+    callback_.Reset();
+  }
   if (native_dialog())
     CloseModalDialog();
 }
 
+void JavaScriptAppModalDialog::RenderViewDeleted(

[Avi (use Gerrit), 2013/10/01 03:20:18]

This really, really makes me sad. The old JavaScript dialog code knew all about
its callers and had a million hooks into them, and this smells of those days.

The WebContentsImpl knows when things are shifting around. Can't it do a better
job of cancelling the dialog if the RVH changes?

[Charlie Reis, 2013/10/01 16:39:29]

That part was optional.  The new WebContents method I added handles all the ways
of the RVH disappearing that I know of, so I went ahead and deleted the
WebContentsObserver stuff here.

+    content::RenderViewHost* render_view_host) {
+  // Don't try to run the callback after the RenderViewHost has been deleted.
+  if (render_view_host_ == render_view_host) {
+    render_view_host_ = NULL;
+    callback_.Reset();
+  }
+}
+
 void JavaScriptAppModalDialog::OnCancel(bool suppress_js_messages) {
   // If we are shutting down and this is an onbeforeunload dialog, cancel the
   // shutdown.
   // TODO(sammc): Remove this when kEnableBatchedShutdown becomes mandatory.
   if (is_before_unload_dialog_ &&
       !CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableBatchedShutdown)) {
     browser_shutdown::SetTryingToQuit(false);
   }
 
@@ skipping 28 matching lines @@
   override_prompt_text_ = override_prompt_text;
   use_override_prompt_text_ = true;
 }
 
 void JavaScriptAppModalDialog::NotifyDelegate(bool success,
                                               const string16& user_input,
                                               bool suppress_js_messages) {
   if (!IsValid())
     return;
 
-  callback_.Run(success, user_input);
+  if (!callback_.is_null()) {
+    callback_.Run(success, user_input);
+    callback_.Reset();
+  }
 
   // The callback_ above may delete web_contents_, thus removing the extra
   // data from the map owned by ChromeJavaScriptDialogManager. Make sure
   // to only use the data if still present. http://crbug.com/236476
-  ExtraDataMap::iterator extra_data = extra_data_map_->find(web_contents());
+  ExtraDataMap::iterator extra_data = extra_data_map_->find(
+      AppModalDialog::web_contents());
   if (extra_data != extra_data_map_->end()) {
     extra_data->second.last_javascript_message_dismissal_ =
         base::TimeTicks::Now();
     extra_data->second.suppress_javascript_messages_ = suppress_js_messages;
   }
 
   // On Views, we can end up coming through this code path twice :(.
   // See crbug.com/63732.
   AppModalDialog::Invalidate();
 }