Add helpers to swipe up and down on the current web view.

ios/chrome/test/earl_grey/chrome_earl_grey_ui.mm

Index: ios/chrome/test/earl_grey/chrome_earl_grey_ui.mm
diff --git a/ios/chrome/test/earl_grey/chrome_earl_grey_ui.mm b/ios/chrome/test/earl_grey/chrome_earl_grey_ui.mm
index 68be6086c5c027c1fc0569fcbd1a7279b953b995..31105abfb9445ba40bb62f4702a3478ab6613884 100644
--- a/ios/chrome/test/earl_grey/chrome_earl_grey_ui.mm
+++ b/ios/chrome/test/earl_grey/chrome_earl_grey_ui.mm
@@ -79,4 +79,18 @@ using testing::kWaitForPageLoadTimeout;
       performAction:grey_tap()];
 }
 
++ (void)swipeUpOnWebView {
+  [[EarlGrey
+      selectElementWithMatcher:WebViewScrollView(
+                                   chrome_test_util::GetCurrentWebState())]
+      performAction:grey_swipeFastInDirection(kGREYDirectionUp)];
+}
+
++ (void)swipeDownOnWebView {
+  [[EarlGrey
+      selectElementWithMatcher:WebViewScrollView(
+                                   chrome_test_util::GetCurrentWebState())]
+      performAction:grey_swipeFastInDirection(kGREYDirectionDown)];
+}
+
 @end