Allow in-progress downloads to show up before DownloadManagerImpl fully initializes

With the introduction of SimpleDownloadManagerCoordinator, it has 2
stages. In the first stage, OnDownloadsInitialized() will be called
for in-progress downloads. In this stage, clients should be able to
access all the in-progress downloads. In the 2nd stage,
OnDownloadsInitialized() is called for all downloads.

However, if InProgressDownloadManager is passed to a
DownloadManagerImpl, the DownloadManagerImpl will not return the
in-progress downloads on GetAllDownloads() unless it is fully initialized.
As a result, this causes a wierd issue that after stage 1, calling
GetAllDownloads() sometimes may not return all the downloads until
stage 2 completes.

BUG=942770

Change-Id: I44e589ee1bd174c5fef86ec9c8170ac94e6e1b5c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1603208Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658795}

content/browser/download/download_manager_impl.cc

@@ -1200,6 +1200,12 @@ download::DownloadItem* DownloadManagerImpl::GetDownload(uint32_t download_id) {
 
 download::DownloadItem* DownloadManagerImpl::GetDownloadByGuid(
     const std::string& guid) {
+  if (!in_progress_downloads_.empty()) {
+    for (const auto& it : in_progress_downloads_) {
+      if (it->GetGuid() == guid)
+        return it.get();
+    }
+  }
   return base::ContainsKey(downloads_by_guid_, guid) ? downloads_by_guid_[guid]
                                                      : nullptr;
 }
@@ -1227,9 +1233,10 @@ void DownloadManagerImpl::OnUrlDownloadStopped(
 
 void DownloadManagerImpl::GetAllDownloads(
     download::SimpleDownloadManager::DownloadVector* downloads) {
-  for (const auto& it : downloads_) {
+  for (const auto& it : downloads_)
     downloads->push_back(it.second.get());
-  }
+  for (const auto& it : in_progress_downloads_)
+    downloads->push_back(it.get());
 }
 
 void DownloadManagerImpl::OpenDownload(download::DownloadItemImpl* download) {

content/browser/download/download_manager_impl_unittest.cc

@@ -765,7 +765,10 @@ TEST_F(DownloadManagerTest, OnInProgressDownloadsLoaded) {
   EXPECT_CALL(GetMockObserver(), OnDownloadCreated(download_manager_.get(), _))
       .WillOnce(Return());
   OnInProgressDownloadManagerInitialized();
-  ASSERT_FALSE(download_manager_->GetDownloadByGuid(kGuid));
+  ASSERT_TRUE(download_manager_->GetDownloadByGuid(kGuid));
+  std::vector<download::DownloadItem*> vector;
+  download_manager_->GetAllDownloads(&vector);
+  ASSERT_EQ(1u, vector.size());
 
   EXPECT_CALL(GetMockDownloadManagerDelegate(), GetNextId(_))
       .WillOnce(RunCallback<0>(1));