Revert "Fix DownloadHistoryCheck on windows continuous builder."

This reverts commit 2dcec349.

Reason for revert: Still flaky, see
https://bugs.chromium.org/p/chromium/issues/detail?id=791213

Original change's description:
> Fix DownloadHistoryCheck on windows continuous builder.
> 
> Currently it's flaky that a partial buffer is read through network
> pipeline when the first history db record is generated.
> 
> This CL changed the observer to be able to optionally wait for a
> certain number of bytes read from network IO.
> 
> Bug: 788160
> Change-Id: I110653433e8c80c2dabf9f3162df99d7bb354e86
> Reviewed-on: https://chromium-review.googlesource.com/790946
> Reviewed-by: Min Qin <qinmin@chromium.org>
> Commit-Queue: Xing Liu <xingliu@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#519930}

TBR=dtrainor@chromium.org,qinmin@chromium.org,xingliu@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 788160
Change-Id: If59f7f82c7bd2a75bbc4655f665fc9f9581e170e
Reviewed-on: https://chromium-review.googlesource.com/804648Reviewed-by: Xing Liu <xingliu@chromium.org>
Commit-Queue: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521233}

chrome/browser/download/download_browsertest.cc

@@ -357,8 +357,7 @@ class HistoryObserver : public DownloadHistory::Observer {
   explicit HistoryObserver(Profile* profile)
       : profile_(profile),
         waiting_(false),
-        seen_stored_(false),
-        minimum_received_bytes_(kNoMinimumReceivedBytes) {
+        seen_stored_(false) {
     DownloadCoreServiceFactory::GetForBrowserContext(profile_)
         ->GetDownloadHistory()
         ->AddObserver(this);
@@ -371,10 +370,6 @@ class HistoryObserver : public DownloadHistory::Observer {
       service->GetDownloadHistory()->RemoveObserver(this);
   }
 
-  void set_minimum_received_bytes(int64_t minimum_received_bytes) {
-    minimum_received_bytes_ = minimum_received_bytes;
-  }
-
   void SetFilterCallback(const FilterCallback& callback) {
     callback_ = callback;
   }
@@ -384,11 +379,6 @@ class HistoryObserver : public DownloadHistory::Observer {
     if (!callback_.is_null() && (!callback_.Run(info)))
         return;
 
-    if (minimum_received_bytes_ != kNoMinimumReceivedBytes &&
-        info.received_bytes < minimum_received_bytes_) {
-      return;
-    }
-
     seen_stored_ = true;
     if (waiting_)
       base::RunLoop::QuitCurrentWhenIdleDeprecated();
@@ -409,11 +399,9 @@ class HistoryObserver : public DownloadHistory::Observer {
   }
 
  private:
-  static const int64_t kNoMinimumReceivedBytes = -1;
   Profile* profile_;
   bool waiting_;
   bool seen_stored_;
-  int64_t minimum_received_bytes_;
   FilterCallback callback_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryObserver);
@@ -1855,7 +1843,13 @@ ServerRedirectRequestHandler(const net::test_server::HttpRequest& request) {
   return std::move(response);
 }
 
-IN_PROC_BROWSER_TEST_F(DownloadTest, DownloadHistoryCheck) {
+#if defined(OS_WIN)
+// https://crbug.com/788160
+#define MAYBE_DownloadHistoryCheck DISABLED_DownloadHistoryCheck
+#else
+#define MAYBE_DownloadHistoryCheck DownloadHistoryCheck
+#endif
+IN_PROC_BROWSER_TEST_F(DownloadTest, MAYBE_DownloadHistoryCheck) {
   // Rediret to the actual download URL.
   embedded_test_server()->RegisterRequestHandler(
       base::Bind(&ServerRedirectRequestHandler));
@@ -1890,8 +1884,6 @@ IN_PROC_BROWSER_TEST_F(DownloadTest, DownloadHistoryCheck) {
   base::Time start(base::Time::Now());
   HistoryObserver observer(browser()->profile());
   observer.SetFilterCallback(base::Bind(&HasDataAndName));
-  observer.set_minimum_received_bytes(
-      content::SlowDownloadHttpResponse::kFirstDownloadSize);
   ui_test_utils::NavigateToURL(browser(), redirect_url);
   observer.WaitForStored();