Animated scroll shouldn't consume unhandled scrolls for OOPIFs.

content/browser/site_per_process_browsertest.cc

Index: content/browser/site_per_process_browsertest.cc
diff --git a/content/browser/site_per_process_browsertest.cc b/content/browser/site_per_process_browsertest.cc
index cb7a479d278c1781ffa6b7d373b786eb0e27a4cf..d09dea79557274885ce0d74ea343c9e71a248e6e 100644
--- a/content/browser/site_per_process_browsertest.cc
+++ b/content/browser/site_per_process_browsertest.cc
@@ -1091,8 +1091,7 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest,
 // Test that scrolling a nested out-of-process iframe bubbles unused scroll
 // delta to a parent frame.
 // Flaky: https://crbug.com/627238
-IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest,
-                       DISABLED_ScrollBubblingFromOOPIFTest) {
+IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest, ScrollBubblingFromOOPIFTest) {
   GURL main_url(embedded_test_server()->GetURL(
       "a.com", "/cross_site_iframe_factory.html?a(b)"));
   EXPECT_TRUE(NavigateToURL(shell(), main_url));
@@ -1192,6 +1191,17 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessBrowserTest,
 
   filter->Reset();
 
+  // TODO(wjmaclean): This is ugly, but it seems that it stops the scroll
+  // we're about to send from occassionally colliding with the previous
+  // scroll animation.
+  {
+    base::RunLoop run_loop;
+    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+        FROM_HERE, run_loop.QuitClosure(), TestTimeouts::action_timeout());
+    run_loop.Run();
+    update_rect = filter->last_rect();
+  }
+
   // Scroll the parent down again in order to test scroll bubbling from
   // gestures.
   scroll_event.delta_y = -5.0f;