Consider empty url case when loading image

third_party/WebKit/Source/web/tests/WebFrameTest.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 12135 matching lines @@
   child->LoadRequest(WebURLRequest(BlankURL()));
 
   // Failing the original child frame navigation and trying to render fallback
   // content shouldn't crash. It should return NoLoadInProgress. This is so the
   // caller won't attempt to replace the correctly empty frame with an error
   // page.
   EXPECT_EQ(WebLocalFrame::NoLoadInProgress,
             child->MaybeRenderFallbackContent(WebURLError()));
 }
 
+TEST_F(WebFrameTest, AltTextOnAboutBlankPage) {
+  FrameTestHelpers::WebViewHelper web_view_helper;
+  web_view_helper.InitializeAndLoad("about:blank", true);
+  web_view_helper.Resize(WebSize(640, 480));
+  WebLocalFrameImpl* frame = web_view_helper.WebView()->MainFrameImpl();
+
+  const char kSource[] =
+      "<img src='foo' alt='foo alt' width='200' height='200'>";

[Nate Chapin, 2017/05/17 17:53:50]

Add id='i' to this...

+  FrameTestHelpers::LoadHTMLString(frame, kSource, ToKURL("about:blank"));
+  web_view_helper.WebView()->UpdateAllLifecyclePhases();
+  RunPendingTasks();
+
+  // Check LayoutText with alt text "foo alt"
+  LayoutObject* root = frame->GetFrame()->ContentLayoutObject();
+  String text = "";
+  for (LayoutObject* obj = root; obj; obj = obj->NextInPreOrder()) {

[Nate Chapin, 2017/05/17 17:53:50]

If I understood dmazzoni's comment correctly, if you add the id to the img tag,
you should be able to do:

LayoutText* layout_text =
ToLayoutText(frame->GetFrame()->GetDocument()->GetElementById("i")->GetLayoutObject()->SlowFirstChild());

..which would avoid the loop.

+    if (obj->IsText()) {
+      LayoutText* layout_text = ToLayoutText(obj);
+      text = layout_text->GetText();
+      break;
+    }
+  }
+  EXPECT_EQ("foo alt", text.Utf8());
+}
+
 }  // namespace blink