Make the UI an observer of downloads.

chrome/browser/download/download_ui_controller.cc

+// Copyright 2013 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/download/download_ui_controller.h"
+
+#include "base/stl_util.h"
+#include "chrome/browser/download/download_item_model.h"
+#include "chrome/browser/ui/browser_finder.h"
+#include "chrome/browser/ui/browser_tabstrip.h"
+#include "content/public/browser/download_item.h"
+#include "content/public/browser/web_contents.h"
+#include "content/public/browser/web_contents_delegate.h"
+
+#if defined(OS_ANDROID)
+#include "content/public/browser/android/download_controller_android.h"
+#else
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/blocked_content/blocked_content_tab_helper.h"
+#include "chrome/browser/ui/blocked_content/blocked_content_tab_helper_delegate.h"
+#endif
+
+namespace {
+
+// DefaultUIControllerDelegate{Android,} is used when a DownloadUIController is
+// constructed without specifying an explicit Delegate.
+#if defined(OS_ANDROID)
+
+class DefaultUIControllerDelegateAndroid
+    : public DownloadUIController::Delegate {
+ public:
+  DefaultUIControllerDelegateAndroid() {}
+  virtual ~DefaultUIControllerDelegateAndroid() {}
+
+ private:
+  // DownloadUIController::Delegate
+  virtual void NotifyDownloadStarting(content::DownloadItem* item) OVERRIDE;
+};
+
+void DefaultUIControllerDelegateAndroid::NotifyDownloadStarting(
+    content::DownloadItem* item) {
+  // GET downloads are delegated to the Android DownloadManager. Chrome is only
+  // responsible for POST downloads.  See
+  // ChromeWebContentsDelegateAndroid::CanDownload().
+  content::DownloadControllerAndroid::Get()->OnPostDownloadStarted(item);
+}
+
+#else  // OS_ANDROID
+
+class DefaultUIControllerDelegate : public DownloadUIController::Delegate {
+ public:
+  // |profile| is required to outlive DefaultUIControllerDelegate.
+  explicit DefaultUIControllerDelegate(Profile* profile)
+      : profile_(profile) {}
+  virtual ~DefaultUIControllerDelegate() {}
+
+ private:
+  // DownloadUIController::Delegate
+  virtual void NotifyDownloadStarting(content::DownloadItem* item) OVERRIDE;
+
+  Profile* profile_;
+};
+
+void DefaultUIControllerDelegate::NotifyDownloadStarting(
+    content::DownloadItem* item) {
+  content::WebContents* web_contents = item->GetWebContents();
+
+  // If the tab requesting the download is a constrained popup that is not
+  // shown, treat the request as if it came from the parent.
+  if (web_contents != NULL) {
+    BlockedContentTabHelper* blocked_content_tab_helper =
+        BlockedContentTabHelper::FromWebContents(web_contents);
+    if (blocked_content_tab_helper &&
+        blocked_content_tab_helper->delegate()) {
+      content::WebContents* constraining_web_contents =
+          blocked_content_tab_helper->delegate()->
+              GetConstrainingWebContents(web_contents);
+      if (constraining_web_contents)
+        web_contents = constraining_web_contents;
+    }
+  }
+
+  Browser* browser =
+      web_contents ? chrome::FindBrowserWithWebContents(web_contents) : NULL;
+
+  // As a last resort, use the last active browser for this profile. Not ideal,
+  // but better than not showing the download at all.
+  if (browser == NULL) {
+    browser = chrome::FindLastActiveWithProfile(profile_,
+                                                chrome::GetActiveDesktop());
+  }
+
+  if (browser)
+    browser->ShowDownload(item);
+}
+
+#endif  // !OS_ANDROID
+
+} // namespace
+
+DownloadUIController::Delegate::~Delegate() {
+}
+
+DownloadUIController::DownloadUIController(content::DownloadManager* manager,
+                                           scoped_ptr<Delegate> delegate)
+    : ALLOW_THIS_IN_INITIALIZER_LIST(download_notifier_(manager, this)),
+      delegate_(delegate.Pass()) {
+  if (!delegate_) {
+#if defined(OS_ANDROID)
+    delegate_.reset(new DefaultUIControllerDelegateAndroid());
+#else
+    // The delegate should not be invoked after the profile has gone away. This
+    // should be the case since DownloadUIController is owned by
+    // DownloadService, which in turn is a profile keyed service.
+    delegate_.reset(new DefaultUIControllerDelegate(
+        Profile::FromBrowserContext(manager->GetBrowserContext())));
+#endif
+  }
+}
+
+DownloadUIController::~DownloadUIController() {
+}
+
+void DownloadUIController::OnDownloadCreated(content::DownloadManager* manager,
+                                             content::DownloadItem* item) {
+  // If this isn't a new download, there's nothing to do.
+  if (!item->IsInProgress())
+    return;
+
+  DownloadItemModel(item).SetShouldNotifyUI(true);
+  // SavePackage downloads are created in a state where they can be shown in the
+  // browser. Call OnDownloadUpdated() once to notify the UI immediately.
+  OnDownloadUpdated(manager, item);
+}
+
+void DownloadUIController::OnDownloadUpdated(content::DownloadManager* manager,
+                                             content::DownloadItem* item) {
+  // Ignore if we've already notified the UI about |item| or if it isn't a new
+  // download.
+  if (!DownloadItemModel(item).ShouldNotifyUI())
+    return;
+
+  // Wait until the target path is determined.
+  if (item->GetTargetFilePath().empty())
+    return;
+
+  // Can't be complete. That would imply that we didn't receive an
+  // OnDownloadUpdated() after the target was determined.
+  DCHECK(!item->IsComplete());
+
+  DownloadItemModel(item).SetShouldNotifyUI(false);
+  delegate_->NotifyDownloadStarting(item);
+}