Quickly close tabs/window with long-running unload handlers.

chrome/browser/ui/unload_detached_handler.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/unload_detached_handler.h"
+
+#include "base/message_loop.h"
+#include "chrome/browser/ui/tab_contents/tab_contents.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "content/public/browser/web_contents.h"
+#include "content/public/browser/web_contents_delegate.h"
+
+namespace chrome {
+
+////////////////////////////////////////////////////////////////////////////////
+// WebContentsDelegate implementation. This owns the TabContents supplied to the
+// constructor.
+class UnloadDetachedHandler::WebContentsDelegateImpl
+    : public content::WebContentsDelegate {
+ public:
+  WebContentsDelegateImpl(UnloadDetachedHandler* handler,
+                          TabContents* tab_contents)
+      : handler_(handler),
+        tab_contents_(tab_contents) {
+    tab_contents->web_contents()->SetDelegate(this);
+  }
+
+  virtual bool ShouldSuppressDialogs() OVERRIDE {
+    return true;  // Return true so dialogs are suppressed.
+  }
+
+  virtual void CloseContents(content::WebContents* source) OVERRIDE {
+    handler_->Destroy(this);
+  }
+
+ private:
+  UnloadDetachedHandler* const handler_;
+  scoped_ptr<TabContents> tab_contents_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(WebContentsDelegateImpl);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+// UnloadDetachedHandler implementation.
+
+UnloadDetachedHandler::UnloadDetachedHandler(const TabsClosedCallback& callback)
+    : tabs_closed_callback_(callback) {
+}
+
+UnloadDetachedHandler::~UnloadDetachedHandler() {
+}
+
+bool UnloadDetachedHandler::DetachWebContents(
+    TabStripModel* tab_strip_model, content::WebContents* web_contents) {
+  if (tab_strip_model->count() > 1) {
+    // Only allow tab to be detached if it is not the last one.
+    // Otherwise, the tab_strip_model would notify the browser that it is empty.
+    // And, the browser would close without waiting for the unload handlers.
+    int index = tab_strip_model->GetIndexOfWebContents(web_contents);
+    if (index != TabStripModel::kNoTab &&
+        web_contents->NeedToFireBeforeUnload()) {
+      TabContents* tab_contents = tab_strip_model->DetachTabContentsAt(index);
+      delegates_.push_back(new WebContentsDelegateImpl(this, tab_contents));

[Ben Goodger (Google), 2012/10/29 22:12:43]

rather than creating a delegate per-tab, can you just have this object be the
delegate for all of them, considering this object will always outlive the tabs?

[slamm, 2012/10/31 18:03:59]

Done. Thats for the suggestion -- much simpler.

+      web_contents->OnUnloadDetachedStarted();
+      return true;
+    }
+  }
+  return false;
+}
+
+bool UnloadDetachedHandler::HasTabs() {
+  return !delegates_.empty();

[Ben Goodger (Google), 2012/10/29 22:12:43]

if you don't have a list of delegates, you can at least carry a list of
webcontentses for this check. if this object is the delegate, you can just
remove the wc from the list in CloseContents().

[slamm, 2012/10/31 18:03:59]

I made a web_contents -> tab_contents map. The tab_contents owns the
web_contents, so the detached handler only deletes the tab_contents.

+}
+
+void UnloadDetachedHandler::Destroy(WebContentsDelegateImpl* delegate) {
+  ScopedVector<WebContentsDelegateImpl>::iterator i =
+      std::find(delegates_.begin(), delegates_.end(), delegate);
+  DCHECK(i != delegates_.end());
+
+  // The delegate's method is a caller on the stack, so schedule the deletion
+  // for later.
+  delegates_.weak_erase(i);
+  MessageLoop::current()->DeleteSoon(FROM_HERE, delegate);
+
+  tabs_closed_callback_.Run();
+}
+
+}  // namespace chrome