[NotLanded] Implement the fetching algorithm of the Web Manifest.

Source/web/WebLocalFrameImpl.cpp

Index: Source/web/WebLocalFrameImpl.cpp
diff --git a/Source/web/WebLocalFrameImpl.cpp b/Source/web/WebLocalFrameImpl.cpp
index b29dbe64f152eed6977f8b870b52a81721fceff3..c673d5d982c4bb31c77bdc1ecfed833d3f33c023 100644
--- a/Source/web/WebLocalFrameImpl.cpp
+++ b/Source/web/WebLocalFrameImpl.cpp
@@ -117,6 +117,7 @@
 #include "core/loader/FrameLoadRequest.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/HistoryItem.h"
+#include "core/loader/ManifestLoader.h"
 #include "core/loader/SubstituteData.h"
 #include "core/page/Chrome.h"
 #include "core/page/EventHandler.h"
@@ -1511,6 +1512,17 @@ WebString WebLocalFrameImpl::layerTreeAsText(bool showDebugInfo) const
     return WebString(frame()->layerTreeAsText(showDebugInfo ? LayerTreeIncludesDebugInfo : LayerTreeNormal));
 }
 
+void WebLocalFrameImpl::requestManifest()
+{
+    if (!frame()) {
+        ASSERT(m_client);
+        m_client->didFailLoadManifest(this, WebManifestError::NoManifest);
+        return;
+    }
+
+    ManifestLoader::loadManifest(PassRefPtr<LocalFrame>(m_frame));
+}
+
 // WebLocalFrameImpl public ---------------------------------------------------------
 
 WebLocalFrame* WebLocalFrame::create(WebFrameClient* client)