Added callback to DownloadUrl() so we can find download failures.

chrome/browser/download/download_test_observer.cc

Index: chrome/browser/download/download_test_observer.cc
diff --git a/chrome/browser/download/download_test_observer.cc b/chrome/browser/download/download_test_observer.cc
index 6e82cc9eef1506c3cf4d84fc231a2523d2a05e71..02038739b2ce12d827c184e650288d24bf4f11eb 100644
--- a/chrome/browser/download/download_test_observer.cc
+++ b/chrome/browser/download/download_test_observer.cc
@@ -346,3 +346,32 @@ void DownloadTestFlushObserver::PingIOThread(int cycle) {
         BrowserThread::UI, FROM_HERE, MessageLoop::QuitClosure());
   }
 }
+
+DownloadTestItemCreationObserver::~DownloadTestItemCreationObserver() {
+}
+
+DownloadTestItemCreationObserver::DownloadTestItemCreationObserver()
+    : called_back_count_(0),
+      waiting_(false),
+      ALLOW_THIS_IN_INITIALIZER_LIST(callback_(base::Bind(
+          &DownloadTestItemCreationObserver::DownloadItemCreationCallback,
+          this))) {
+}
+
+void DownloadTestItemCreationObserver::WaitForDownloadItemCreation() {
+  if (called_back_count_ == 0) {
+    waiting_ = true;
+    ui_test_utils::RunMessageLoop();
+    waiting_ = false;
+  }
+}
+
+void DownloadTestItemCreationObserver::DownloadItemCreationCallback(
+    content::DownloadId download_id, net::Error error) {
+  creation_info_.download_id = download_id;

[cbentzel, 2012/03/02 21:00:18]

Can you add a DCHECK that this is called on the UI thread? 

[ahendrickson, 2012/03/02 21:51:41]

Done.

+  creation_info_.error = error;
+  ++called_back_count_;
+
+  if (waiting_ && (called_back_count_ > 0))
+    MessageLoopForUI::current()->Quit();
+}