Make web store resilient against download completion happening before opening.

content/public/test/download_test_observer.cc

Index: content/public/test/download_test_observer.cc
diff --git a/content/public/test/download_test_observer.cc b/content/public/test/download_test_observer.cc
index 85caf410ade5d3706840c7ca8ac9ebf8c7d99b43..b35aa78889d2d9b5b4b01d67dedc009e49ee60ba 100644
--- a/content/public/test/download_test_observer.cc
+++ b/content/public/test/download_test_observer.cc
@@ -44,6 +44,45 @@ void DenyDangerousDownload(scoped_refptr<DownloadManager> download_manager,
 
 }  // namespace
 
+DownloadUpdatedObserver::DownloadUpdatedObserver(
+    DownloadItem* item, DownloadUpdatedObserver::EventFilter filter)
+    : item_(item), filter_(filter), waiting_(false) {
+  item->AddObserver(this);
+}
+
+DownloadUpdatedObserver::~DownloadUpdatedObserver() {
+  if (item_)
+    item_->RemoveObserver(this);
+}
+
+bool DownloadUpdatedObserver::WaitForEvent() {
+  if (item_ && filter_.Run(item_))
+    return true;
+
+  waiting_ = true;
+  RunMessageLoop();
+  waiting_ = false;
+
+  if (!item_)
+    return false;
+
+  return true;

[benjhayden, 2012/09/10 14:48:52]

Are you sure that OnDownloadDestroyed() will never run between
OnDownloadUpdated() and MessageLoop::Quit()? Couldn't hurt to double-check
filter_.Run(item_) here, could it?

[Randy Smith (Not in Mondays), 2012/09/10 17:16:42]

I'm not quite sure the race you're protecting against, but OnDownloadDestroyed()
happening after OnDownloadUpdated() and before the return from the message loop
would result in a false negative, so I rewrite the class to protect against
that.  Let me know what you think.

+}
+
+void DownloadUpdatedObserver::OnDownloadUpdated(DownloadItem* item) {
+  DCHECK_EQ(item_, item);
+  if (waiting_ && filter_.Run(item_))
+    MessageLoopForUI::current()->Quit();
+}
+
+void DownloadUpdatedObserver::OnDownloadDestroyed(DownloadItem* item) {
+  DCHECK_EQ(item_, item);
+  item_->RemoveObserver(this);
+  item_ = NULL;
+  if (waiting_)
+    MessageLoopForUI::current()->Quit();
+}
+
 DownloadTestObserver::DownloadTestObserver(
     DownloadManager* download_manager,
     size_t wait_count,