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..877d39fc0ddb2627075c4e2abfb17bdcc9a74c3e 100644
--- a/content/public/test/download_test_observer.cc
+++ b/content/public/test/download_test_observer.cc
@@ -44,6 +44,43 @@ void DenyDangerousDownload(scoped_refptr<DownloadManager> download_manager,
 
 }  // namespace
 
+DownloadUpdatedObserver::DownloadUpdatedObserver(
+    DownloadItem* item, DownloadUpdatedObserver::EventFilter filter)
+    : item_(item), filter_(filter), waiting_(false), event_seen_(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;
+  return event_seen_;

[benjhayden, 2012/09/10 17:37:29]

Nice!

What if WaitForEvent() is called on the same DUO twice?
bool seen = event_seen_;
event_seen_ = false;
return seen;

[Randy Smith (Not in Mondays), 2012/09/10 18:32:34]

I think of this type of class as tracking whether the event occurred in the
window between when the class is constructed and when WaitForEvent() is called. 
For that, event_seen_ shouldn't be reset.  Having said that, it *should* be
tested upon entry so that you don't wait forever.  I'll fix that.  

+}
+
+void DownloadUpdatedObserver::OnDownloadUpdated(DownloadItem* item) {
+  DCHECK_EQ(item_, item);
+  if (filter_.Run(item_))
+    event_seen_ = true;
+  if (waiting_ && event_seen_)
+    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,