[Download Notification] Refine retry logic when interrupted or cancelled

chrome/browser/download/download_commands.cc

Index: chrome/browser/download/download_commands.cc
diff --git a/chrome/browser/download/download_commands.cc b/chrome/browser/download/download_commands.cc
index 97784977e39b20f3f88b82ed0210bc26bebca988..32151569955c3e83004af7d0fd8ac5735e75ad26 100644
--- a/chrome/browser/download/download_commands.cc
+++ b/chrome/browser/download/download_commands.cc
@@ -15,6 +15,8 @@
 #include "chrome/browser/ui/scoped_tabbed_browser_displayer.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/generated_resources.h"
+#include "content/public/browser/download_manager.h"
+#include "content/public/browser/download_url_parameters.h"
 #include "grit/theme_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
@@ -136,6 +138,8 @@ bool DownloadCommands::IsCommandVisible(Command command) const {
 }
 
 void DownloadCommands::ExecuteCommand(Command command) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
   switch (command) {
     case SHOW_IN_FOLDER:
       download_item_->ShowDownloadInShell();
@@ -203,13 +207,23 @@ void DownloadCommands::ExecuteCommand(Command command) {
     case RESUME:
       download_item_->Resume();
       break;
-    case RETRY:
-      if (download_item_->CanResume()) {
-        download_item_->Resume();
-      } else {
-        // TODO(yoshiki): Implement retry logic.
-      }
+    case RETRY: {
+      content::DownloadManager* download_manager =
+          content::BrowserContext::GetDownloadManager(
+              download_item_->GetBrowserContext());
+      scoped_ptr<content::DownloadUrlParameters> params(
+          content::DownloadUrlParameters::FromWebContents(
+              download_item_->GetWebContents(), download_item_->GetURL()));

[asanka, 2015/04/22 21:17:35]

DownloadItem::GetWebContents() isn't guaranteed to return a non-null result.
This is going to fail for a substantial number of cases.

+      params->set_referrer(content::Referrer(download_item_->GetReferrerUrl(),
+                           blink::WebReferrerPolicyDefault));
+
+      // Removes the previous donwload item.
+      download_item_->Remove();
+
+      // Starts new download.
+      download_manager->DownloadUrl(params.Pass());
       break;
+    }
   }
 }