Deflake data saver savings browser tests

Bug: 984925
TBR: ryansturm@chromium.org
Change-Id: I55ba7765926ce316f4bbe5d6911858a0a7b41fc0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1769157
Commit-Queue: rajendrant <rajendrant@chromium.org>
Reviewed-by: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#690215}

chrome/browser/page_load_metrics/observers/data_saver_site_breakdown_metrics_observer_browsertest.cc

@@ -226,6 +226,7 @@ IN_PROC_BROWSER_TEST_F(DataSaverSiteBreakdownMetricsObserverBrowserTest,
       {"/media/youtube.html", 5000, 20000},
   };
   ASSERT_TRUE(embedded_test_server()->Start());
+  WaitForDBToInitialize();
 
   for (const auto& test : tests) {
     GURL test_url(embedded_test_server()->GetURL(test.url));
@@ -255,6 +256,7 @@ IN_PROC_BROWSER_TEST_F(DataSaverSiteBreakdownMetricsObserverBrowserTest,
   plaintext_server->RegisterRequestHandler(
       base::BindRepeating(&HandleResourceRequestWithPlaintextMimeType));
   ASSERT_TRUE(plaintext_server->Start());
+  WaitForDBToInitialize();
 
   GURL test_url(plaintext_server->GetURL("/page"));