Wait for button to become active before clicking it.

BUG=411143

Review URL: https://codereview.chromium.org/544403002

Cr-Commit-Position: refs/heads/master@{#294092}

chrome/test/remoting/remote_desktop_browsertest.cc

@@ -309,9 +309,8 @@ void RemoteDesktopBrowserTest::Approve() {
               &RemoteDesktopBrowserTest::IsAuthenticatedInWindow,
               browser()->tab_strip_model()->GetActiveWebContents()));
 
-    ExecuteScript(
-        "lso.approveButtonAction();"
-        "document.forms[\"connect-approve\"].submit();");
+    // Click to Approve the web-app.
+    ClickOnControl("submit_approve_access");
 
     observer.Wait();
 
@@ -708,6 +707,13 @@ void RemoteDesktopBrowserTest::RunJavaScriptTest(
 void RemoteDesktopBrowserTest::ClickOnControl(const std::string& name) {
   ASSERT_TRUE(HtmlElementVisible(name));
 
+  ConditionalTimeoutWaiter waiter(
+        base::TimeDelta::FromSeconds(5),
+        base::TimeDelta::FromMilliseconds(500),
+        base::Bind(&RemoteDesktopBrowserTest::IsEnabled,
+          active_web_contents(), name));
+  ASSERT_TRUE(waiter.Wait());
+
   ExecuteScript("document.getElementById(\"" + name + "\").click();");
 }
 
@@ -801,4 +807,13 @@ bool RemoteDesktopBrowserTest::IsHostActionComplete(
       host_action_var);
 }
 
+// static
+bool RemoteDesktopBrowserTest::IsEnabled(
+    content::WebContents* client_web_content,
+    const std::string& element_name) {
+  return !ExecuteScriptAndExtractBool(
+    client_web_content,
+    "document.getElementById(\"" + element_name + "\").disabled");
+}
+
 }  // namespace remoting

chrome/test/remoting/remote_desktop_browsertest.h

@@ -314,6 +314,11 @@ class RemoteDesktopBrowserTest : public extensions::PlatformAppBrowserTest {
       return IsAuthenticatedInWindow(active_web_contents());
   }
 
+  // Callback used by Approve to check whether the Accept button is enabled
+  // and ready to receive a click.
+  static bool IsEnabled(
+      content::WebContents* web_contents, const std::string& name);
+
   // If the "Host version out-of-date" form is visible, dismiss it.
   void DismissHostVersionWarningIfVisible();