[ios] Fix NTP scroll tests.

Start the scroll from the middle of the screen incase the default bottom of the
screen is obscured by the bottom toolbar and stop using kGREYContentEdgeBottom.

BUG: 825431
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I704954672bf46e9cb138ea0be6a325ba4aeb3d69
Reviewed-on: https://chromium-review.googlesource.com/1028462Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553805}

ios/chrome/browser/ui/content_suggestions/content_suggestions_egtest.mm

@@ -101,10 +101,14 @@ ContentSuggestion Suggestion(Category category,
 // 200 is a reasonable scroll displacement that works for all UI elements, while
 // not being too slow.
 GREYElementInteraction* CellWithMatcher(id<GREYMatcher> matcher) {
+  // Start the scroll from the middle of the screen in case the bottom of the
+  // screen is obscured by the bottom toolbar.
+  id<GREYAction> action =
+      grey_scrollInDirectionWithStartPoint(kGREYDirectionDown, 200, 0.5, 0.5);
   return [[EarlGrey
       selectElementWithMatcher:grey_allOf(matcher, grey_sufficientlyVisible(),
                                           nil)]
-         usingSearchAction:grey_scrollInDirection(kGREYDirectionDown, 200)
+         usingSearchAction:action
       onElementWithMatcher:chrome_test_util::ContentSuggestionCollectionView()];
 }
 
@@ -522,12 +526,13 @@ GREYElementInteraction* CellWithMatcher(id<GREYMatcher> matcher) {
 // Tests that the "Learn More" cell is present only if there is a suggestion in
 // the section.
 - (void)testLearnMore {
-  [[EarlGrey selectElementWithMatcher:chrome_test_util::
-                                          ContentSuggestionCollectionView()]
-      performAction:grey_scrollToContentEdge(kGREYContentEdgeBottom)];
-  [[EarlGrey selectElementWithMatcher:grey_accessibilityID(
-                                          [ContentSuggestionsLearnMoreItem
-                                              accessibilityIdentifier])]
+  id<GREYAction> action =
+      grey_scrollInDirectionWithStartPoint(kGREYDirectionDown, 200, 0.5, 0.5);
+  [[[EarlGrey selectElementWithMatcher:grey_accessibilityID(
+                                           [ContentSuggestionsLearnMoreItem
+                                               accessibilityIdentifier])]
+         usingSearchAction:action
+      onElementWithMatcher:chrome_test_util::ContentSuggestionCollectionView()]
       assertWithMatcher:grey_nil()];
 
   std::vector<ContentSuggestion> suggestions;