Print Preview: Print in the background.

chrome/browser/printing/background_printing_manager.cc

+// 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/printing/background_printing_manager.h"
+
+#include "chrome/browser/printing/print_job.h"
+#include "chrome/browser/tabs/tab_strip_model.h"
+#include "chrome/browser/ui/browser_list.h"
+#include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
+#include "content/browser/browser_thread.h"
+#include "content/common/notification_details.h"
+#include "content/common/notification_source.h"
+
+namespace printing {
+
+BackgroundPrintingManager::BackgroundPrintingManager() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+}
+
+BackgroundPrintingManager::~BackgroundPrintingManager() {
+  DCHECK_EQ(0U, printing_contents_.size());

[sky, 2011/05/06 16:37:55]

Its the browsers that keep the process alive, not the tabcontents. So, if you
print the last tab in the background and close all browsers then this could hit.

If you want to make sure chrome doesn't exit in this case HideTabContents needs
to up the ref count of the browser_process. Having said that, it seems if the
user closes all tabs and there is a print process under you way you would want
to show some dialog.

[Lei Zhang, 2011/05/06 18:49:01]

Indeed, thanks for mentioning this corner case. I'll look into fixing this.

I don't think we show a dialog right now when the user quits and printing is in
progress. I can certainly try to improve this, but I don't think the behavior is
any worse than what we have right now.

+}
+
+void BackgroundPrintingManager::HideTabContents(TabContentsWrapper* contents) {
+  CHECK(printing_contents_.find(contents) == printing_contents_.end());
+
+  printing_contents_.insert(contents);
+
+  registrar_.Add(this, NotificationType::PRINT_JOB_RELEASED,
+                 Source<TabContents>(contents->tab_contents()));
+  registrar_.Add(this, NotificationType::TAB_CONTENTS_DESTROYED,
+                 Source<TabContents>(contents->tab_contents()));
+
+  // Detach |contents| from its tab strip.
+  Browser* browser = BrowserList::FindBrowserWithID(
+      contents->controller().window_id().id());
+  TabStripModel* tabstrip = browser->tabstrip_model();
+  tabstrip->DetachTabContentsAt(tabstrip->GetIndexOfTabContents(contents));
+}
+
+void BackgroundPrintingManager::Observe(NotificationType type,
+                                        const NotificationSource& source,
+                                        const NotificationDetails& details) {
+  switch (type.value) {
+    case NotificationType::PRINT_JOB_RELEASED: {
+      // This might be happening in the middle of a RenderViewGone() loop.
+      // Deleting |contents| later so the RenderViewGone() loop can finish.
+      MessageLoop::current()->DeleteSoon(FROM_HERE,
+                                         Source<TabContents>(source).ptr());
+      break;
+    }
+    case NotificationType::TAB_CONTENTS_DESTROYED: {
+      TabContents* contents = Source<TabContents>(source).ptr();
+      registrar_.Remove(this, NotificationType::PRINT_JOB_RELEASED,
+                        Source<TabContents>(contents));
+      registrar_.Remove(this, NotificationType::TAB_CONTENTS_DESTROYED,
+                        Source<TabContents>(contents));
+      printing_contents_.erase(
+          TabContentsWrapper::GetCurrentWrapperForContents(contents));
+      break;
+    }
+    default: {
+      NOTREACHED();
+      break;
+    }
+  }
+}
+
+std::set<TabContentsWrapper*>::const_iterator
+    BackgroundPrintingManager::begin() {
+  return printing_contents_.begin();
+}
+
+std::set<TabContentsWrapper*>::const_iterator
+    BackgroundPrintingManager::end() {
+  return printing_contents_.end();
+}
+
+}  // namespace printing