Make the context menu test more resilient against clicking on text.

If the right click happens on top of text, then on Mac the text will
become selected before showing the context menu, leading to different
context menu items being shown.  This CL starts to use an empty subframe
to avoid this problem.  This helps enable the test on Mac platform.

Bug: 1090891
Change-Id: Ie4f78aa6adaa36d970e0f538fc80f28b09eb0592
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2229658
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776371}

chrome/browser/renderer_context_menu/render_view_context_menu_browsertest.cc

@@ -69,6 +69,7 @@
 #include "content/public/common/content_features.h"
 #include "content/public/test/browser_test.h"
 #include "content/public/test/browser_test_utils.h"
+#include "content/public/test/test_navigation_observer.h"
 #include "content/public/test/test_utils.h"
 #include "extensions/browser/api/extensions_api_client.h"
 #include "extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h"
@@ -936,22 +937,28 @@ IN_PROC_BROWSER_TEST_F(ContextMenuBrowserTest,
               testing::Not(testing::Contains(IDC_CONTENT_CONTEXT_RELOADFRAME)));
 }
 
-#if defined(OS_MACOSX)
-// TODO(lukasza): https://crbug.com/1090891: Subframe behavior is unexpected on
-// some Mac bots.
-#define MAYBE_MenuContentsVerification_Subframe \
-  DISABLED_MenuContentsVerification_Subframe
-#else
-#define MAYBE_MenuContentsVerification_Subframe \
-  MenuContentsVerification_Subframe
-#endif
 // Check which commands are present after opening the context menu for a
 // subframe.
 IN_PROC_BROWSER_TEST_F(ContextMenuBrowserTest,
-                       MAYBE_MenuContentsVerification_Subframe) {
+                       MenuContentsVerification_Subframe) {
   ASSERT_TRUE(embedded_test_server()->Start());
   GURL url(embedded_test_server()->GetURL("/iframe.html"));
   ui_test_utils::NavigateToURL(browser(), url);
+  content::WebContents* tab =
+      browser()->tab_strip_model()->GetActiveWebContents();
+
+  // Make sure the subframe doesn't contain any text, because the context menu
+  // may behave differently when opened over text selection.  See also
+  // https://crbug.com/1090891.
+  {
+    content::TestNavigationObserver nav_observer(tab, 1);
+    const char kScript[] = R"(
+        var frame = document.getElementsByTagName('iframe')[0];
+        frame.src = 'data:text/html;charset=utf-8,%3Cbody%3E%3C%2Fbody%3E';
+    )";
+    ASSERT_TRUE(content::ExecJs(tab, kScript));
+    nav_observer.Wait();
+  }
 
   // Open a context menu.
   ContextMenuWaiter menu_observer;
@@ -961,8 +968,6 @@ IN_PROC_BROWSER_TEST_F(ContextMenuBrowserTest,
       blink::WebInputEvent::GetStaticTimeStampForTests());
   mouse_event.button = blink::WebMouseEvent::Button::kRight;
   mouse_event.SetPositionInWidget(25, 25);  // This is over the subframe.
-  content::WebContents* tab =
-      browser()->tab_strip_model()->GetActiveWebContents();
   tab->GetRenderViewHost()->GetWidget()->ForwardMouseEvent(mouse_event);
   mouse_event.SetType(blink::WebInputEvent::Type::kMouseUp);
   tab->GetRenderViewHost()->GetWidget()->ForwardMouseEvent(mouse_event);