Fix testContextMenuOpenInNewTabFromTallPage.

ios/chrome/browser/context_menu/context_menu_egtest.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import <EarlGrey/EarlGrey.h>
 #import <UIKit/UIKit.h>
 #import <XCTest/XCTest.h>
 
 #include "base/strings/sys_string_conversions.h"
 #include "ios/chrome/browser/ui/ui_util.h"
@@ skipping 171 matching lines @@
   // Verify url and tab count.
   [[EarlGrey selectElementWithMatcher:chrome_test_util::OmniboxText(
                                           destinationURL.GetContent())]
       assertWithMatcher:grey_notNil()];
   chrome_test_util::AssertMainTabCount(2U);
 }
 
 // Tests "Open in New Tab" on context menu  on a link that requires scrolling
 // on the page to verify that context menu can be properly triggered in the
 // current screen view.
-// TODO(crbug.com/701104): This test is flaky because sometimes it doesn't
-// scroll down far enough for the link to be visible.
-- (void)FLAKY_testContextMenuOpenInNewTabFromTallPage {
+- (void)testContextMenuOpenInNewTabFromTallPage {
   // Set up test simple http server.
   std::map<GURL, std::string> responses;
   GURL initialURL =
       web::test::HttpServer::MakeUrl("http://scenarioContextMenuOpenInNewTab");
   GURL destinationURL = web::test::HttpServer::MakeUrl("http://destination");
 
   // The initial page contains a link to the destination page that is below a
   // really tall div so that scrolling is required.
   responses[initialURL] =
       "<div style='height:4000px'></div>"
       "<a style='margin-left:50px' href='" +
       destinationURL.spec() + "' id='link'>link</a>";
   responses[destinationURL] = kDestinationHtml;
 
   web::test::SetUpSimpleHttpServer(responses);
   [ChromeEarlGrey loadURL:initialURL];
   chrome_test_util::AssertMainTabCount(1U);
 
   // Scroll down on the web view to make the link visible.
+  // grey_swipeFastInDirecton will quickly scroll towards the bottom, and then
+  // grey_scrollToContentEdge guarantees the content edge is reached. Two
+  // methods are used because the first one is much faster, but doesn't
+  // guarantee the link becomes visible.
   [[EarlGrey
       selectElementWithMatcher:WebViewScrollView(
                                    chrome_test_util::GetCurrentWebState())]
       performAction:grey_swipeFastInDirection(kGREYDirectionUp)];
+  [[EarlGrey
+      selectElementWithMatcher:WebViewScrollView(
+                                   chrome_test_util::GetCurrentWebState())]
+      performAction:grey_scrollToContentEdge(kGREYContentEdgeBottom)];

[Eugene But (OOO till 7-30), 2017/03/16 16:54:52]

It's pretty bad that |grey_scrollToContentEdge| is so slow that callers have to
use |grey_swipeFastInDirection| first. Do you want to file a bug against EG and
add a TODO to clean this up?

[baxley, 2017/03/16 17:05:14]

Done.
Yeah, I agree that it's so slow. For a lot of tests it can be fine to just use
that, but this is a really long webpage. I filed a bug to track this, and I'll
reply to the existing EG issue about this to see if they want to do that. The
downside is it adds even more scroll/swipe APIs, but it doesn't hurt to address
it.

+
   [[EarlGrey selectElementWithMatcher:chrome_test_util::WebViewContainingText(
                                           kDestinationLinkID)]
       assertWithMatcher:grey_notNil()];
 
   LongPressElementAndTapOnButton(kDestinationLinkID, OpenLinkInNewTabButton());
 
   // Earl Grey cannot preperly synchronize some animations, so adding a
   // WaitUntilCondition to wait for the new tab opening animation to finish
   // and the scroll view to become interactable.
   ConditionBlock condition = ^{
@@ skipping 20 matching lines @@
   SelectTabAtIndexInCurrentMode(1U);
 
   // Verify url and tab count.
   [[EarlGrey selectElementWithMatcher:chrome_test_util::OmniboxText(
                                           destinationURL.GetContent())]
       assertWithMatcher:grey_notNil()];
   chrome_test_util::AssertMainTabCount(2U);
 }
 
 @end