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

ios/chrome/test/earl_grey/chrome_earl_grey_ui.h

Index: ios/chrome/test/earl_grey/chrome_earl_grey_ui.h
diff --git a/ios/chrome/test/earl_grey/chrome_earl_grey_ui.h b/ios/chrome/test/earl_grey/chrome_earl_grey_ui.h
index 792001a296045542e2b72992ec74ce3dfd50f454..ff5da40e2c60947db1f07685e193b62201aab42f 100644
--- a/ios/chrome/test/earl_grey/chrome_earl_grey_ui.h
+++ b/ios/chrome/test/earl_grey/chrome_earl_grey_ui.h
@@ -29,6 +29,16 @@
 // Requires having a tab opened.
 + (void)openShareMenu;
 
+// Swipes up on the current web view, hiding the toolbar if it is present and
+// hideable. It attempts to swipe to the bottom of the page in the web view, but
+// if the toolbar disappears it can prevent it from making all the way to the
+// bottom. Induces a GREYAssert if no web view is present.
++ (void)swipeUpOnWebView;
+
+// Swipes down on the current web view, showing the toolbar if it is hidden and
+// able to be shown. Induces a GREYAssert if no web view is present.
++ (void)swipeDownOnWebView;
+
 @end
 
 #endif  // IOS_CHROME_TEST_EARL_GREY_CHROME_EARL_GREY_UI_H_