Make the UI an observer of downloads.

chrome/browser/ui/browser.cc

 // Copyright 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/browser.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #endif  // defined(OS_WIN)
@@ skipping 1316 matching lines @@
   // If |mode| is |SEARCH_SUGGESTIONS| and bookmark bar is still showing
   // attached, the previous mode is definitely NTP; it won't be |DEFAULT|
   // because ModeChanged() would have handled that transition by hiding the
   // bookmark bar.
   if (mode.is_search_suggestions() &&
       bookmark_bar_state_ == BookmarkBar::SHOW) {
     UpdateBookmarkBarState(BOOKMARK_BAR_STATE_CHANGE_INSTANT_PREVIEW_STATE);
   }
 }
 
+void Browser::ShowDownload(content::DownloadItem* download) {

[benjhayden, 2012/12/20 21:09:14]

Can this method be moved out to the Observer? It looks like it doesn't use
anything in the Browser except window(), which is public, and CloseContents,
which could be accessed by up-casting the Browser*. If you don't want to up-cast
it, could you move the rest of this method out into the Observer?

[asanka, 2012/12/20 22:41:19]

The Browser class:
- Handles closing the tab that initiated the download if that was the only thing
that the tab did.
- Handles showing the download in the shelf.
- Handles displaying the "download started" animation.

The DownloadUIController class:
- Figures out which Browser to notify and notifies it.

I think this is a reasonable layering scheme. I don't think DownloadUIController
should reach into a Browser object and close its tabs or insert downloads into
the shelf or trigger animations, even if its possible with the API.

+  scoped_ptr<DownloadItemModel> download_model(new DownloadItemModel(download));
+  if (!window())
+    return;
+
+  // If the download occurs in a new tab, and it's not a save page
+  // download (started before initial navigation completed) close it.
+  WebContents* source = download->GetWebContents();
+  if (source && source->GetController().IsInitialNavigation() &&
+      tab_count() > 1 && !download->IsSavePackageDownload()) {
+    CloseContents(source);
+  }
+
+  // Some (app downloads) are not supposed to appear on the shelf.
+  if (!download_model->ShouldShowInShelf())
+    return;
+
+  // GetDownloadShelf creates the download shelf if it was not yet created.
+  DownloadShelf* shelf = window()->GetDownloadShelf();
+  shelf->AddDownload(download_model.release());
+  // Don't show the animation for "Save file" downloads.
+  // For non-theme extensions, we don't show the download animation.
+  // Show animation in same window as the download shelf. Download shelf
+  // may not be in the same window that initiated the download.
+  // Don't show the animation if the selected tab is not visible (i.e. the
+  // window is minimized, we're in a unit test, etc.).
+  WebContents* shelf_tab = chrome::GetActiveWebContents(shelf->browser());
+  if ((download->GetTotalBytes() > 0) &&
+      !download_crx_util::IsExtensionDownload(*download) &&
+      platform_util::IsVisible(shelf_tab->GetNativeView()) &&
+      ui::Animation::ShouldRenderRichAnimation()) {
+    DownloadStartedAnimation::Show(shelf_tab);
+  }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Browser, content::WebContentsDelegate implementation:
 
 WebContents* Browser::OpenURLFromTab(WebContents* source,
                                      const OpenURLParams& params) {
   chrome::NavigateParams nav_params(this, params.url, params.transition);
   nav_params.source_contents = source;
   nav_params.referrer = params.referrer;
   nav_params.extra_headers = params.extra_headers;
   nav_params.disposition = params.disposition;
@@ skipping 141 matching lines @@
 }
 
 void Browser::RenderWidgetShowing() {
   window_->DisableInactiveFrame();
 }
 
 int Browser::GetExtraRenderViewHeight() const {
   return window_->GetExtraRenderViewHeight();
 }
 
-void Browser::OnStartDownload(WebContents* source,
-                              content::DownloadItem* download) {
-  scoped_ptr<DownloadItemModel> download_model(new DownloadItemModel(download));
-  if (!download_model->ShouldShowInShelf())
-    return;
-
-  WebContents* constrained = GetConstrainingWebContents(source);
-  if (constrained != source) {
-    // Download in a constrained popup is shown in the tab that opened it.
-    constrained->GetDelegate()->OnStartDownload(constrained, download);
-    return;
-  }
-
-  if (!window())
-    return;
-
-  // GetDownloadShelf creates the download shelf if it was not yet created.
-  DownloadShelf* shelf = window()->GetDownloadShelf();
-  shelf->AddDownload(download_model.release());
-  // Don't show the animation for "Save file" downloads.
-  // For non-theme extensions, we don't show the download animation.
-  // Show animation in same window as the download shelf. Download shelf
-  // may not be in the same window that initiated the download.
-  // Don't show the animation if the selected tab is not visible (i.e. the
-  // window is minimized, we're in a unit test, etc.).
-  WebContents* shelf_tab = chrome::GetActiveWebContents(shelf->browser());
-  if ((download->GetTotalBytes() > 0) &&
-      !download_crx_util::IsExtensionDownload(*download) &&
-      platform_util::IsVisible(shelf_tab->GetNativeView()) &&
-      ui::Animation::ShouldRenderRichAnimation()) {
-    DownloadStartedAnimation::Show(shelf_tab);
-  }
-
-  // If the download occurs in a new tab, and it's not a save page
-  // download (started before initial navigation completed) close it.
-  if (source->GetController().IsInitialNavigation() && tab_count() > 1 &&
-      !download->IsSavePackageDownload())
-    CloseContents(source);
-}
-
 void Browser::ViewSourceForTab(WebContents* source, const GURL& page_url) {
   DCHECK(source);
   chrome::ViewSource(this, source);
 }
 
 void Browser::ViewSourceForFrame(WebContents* source,
                                  const GURL& frame_url,
                                  const std::string& frame_content_state) {
   DCHECK(source);
   chrome::ViewSource(this, source, frame_url, frame_content_state);
@@ skipping 893 matching lines @@
   if (contents && !allow_js_access) {
     contents->web_contents()->GetController().LoadURL(
         target_url,
         content::Referrer(),
         content::PAGE_TRANSITION_LINK,
         std::string());  // No extra headers.
   }
 
   return contents != NULL;
 }