Add ability to submit a form using javascript.

BUG=none

Review-Url: https://codereview.chromium.org/2283963002
Cr-Commit-Position: refs/heads/master@{#414854}

ios/web/public/test/web_view_interaction_test_util.h

@@ -19,5 +19,9 @@ bool TapWebViewElementWithId(web::WebState* web_state,
 bool FocusWebViewElementWithId(web::WebState* web_state,
                                const std::string& element_id);
 
+// Returns whether the form with |form_id| in the passed |web_state| has been
+// submitted using a JavaScript submit() event.
+bool SubmitWebViewFormWithId(web::WebState* web_state,
+                             const std::string& form_id);
 }  // namespace test
 }  // namespace web

ios/web/public/test/web_view_interaction_test_util.mm

@@ -15,7 +15,11 @@ using web::NavigationManager;
 namespace web {
 namespace test {
 
-enum ElementAction { ELEMENT_ACTION_CLICK, ELEMENT_ACTION_FOCUS };
+enum ElementAction {
+  ELEMENT_ACTION_CLICK,
+  ELEMENT_ACTION_FOCUS,
+  ELEMENT_ACTION_SUBMIT
+};
 
 // Returns whether the Javascript action specified by |action| ran on
 // |element_id| in the passed |web_state|.
@@ -32,6 +36,9 @@ bool RunActionOnWebViewElementWithId(web::WebState* web_state,
     case ELEMENT_ACTION_FOCUS:
       js_action = ".focus();";
       break;
+    case ELEMENT_ACTION_SUBMIT:
+      js_action = ".submit();";
+      break;
   }
   NSString* script = [NSString
       stringWithFormat:@"(function() {"
@@ -70,5 +77,11 @@ bool FocusWebViewElementWithId(web::WebState* web_state,
                                          ELEMENT_ACTION_FOCUS);
 }
 
+bool SubmitWebViewFormWithId(web::WebState* web_state,
+                             const std::string& form_id) {
+  return RunActionOnWebViewElementWithId(web_state, form_id,
+                                         ELEMENT_ACTION_SUBMIT);
+}
+
 }  // namespace test
 }  // namespace web