Adds an experiment that enabled SuggestionsService suggestions (MostLikely) on LocalNTP

chrome/renderer/searchbox/searchbox_extension.cc

Index: chrome/renderer/searchbox/searchbox_extension.cc
diff --git a/chrome/renderer/searchbox/searchbox_extension.cc b/chrome/renderer/searchbox/searchbox_extension.cc
index 17e7bf15a118c7bc1cc64b0afbdc8239a520900a..5dac68e71fa6b221d9002715f9bec734417a3404 100644
--- a/chrome/renderer/searchbox/searchbox_extension.cc
+++ b/chrome/renderer/searchbox/searchbox_extension.cc
@@ -152,8 +152,30 @@ v8::Local<v8::Object> GenerateMostVisitedItem(
            v8::Int32::New(isolate, render_view_id));
   obj->Set(v8::String::NewFromUtf8(isolate, "rid"),
            v8::Int32::New(isolate, restricted_id));
-  obj->Set(v8::String::NewFromUtf8(isolate, "thumbnailUrl"),
-           GenerateThumbnailURL(isolate, render_view_id, restricted_id));
+
+  // If the suggestion already has a suggested thumbnail, we create an thumbnail
+  // array with both the local thumbnail and the proposed one.
+  // Otherwise, we just create an array with the generated one.
+  if (!mv_item.thumbnail.spec().empty()) {
+    v8::Local<v8::Array> thumbs = v8::Array::New(isolate, 2);
+    thumbs->Set(0, UTF8ToV8String(isolate, base::StringPrintf(
+                                               "chrome-search://thumb2/%s",
+                                               mv_item.url.spec().c_str())));
+    thumbs->Set(1, UTF8ToV8String(isolate, mv_item.thumbnail.spec()));
+    obj->Set(v8::String::NewFromUtf8(isolate, "thumbnailUrls"), thumbs);
+  } else {
+    v8::Local<v8::Array> thumbs = v8::Array::New(isolate, 1);
+    thumbs->Set(0,
+                GenerateThumbnailURL(isolate, render_view_id, restricted_id));
+    obj->Set(v8::String::NewFromUtf8(isolate, "thumbnailUrls"), thumbs);
+  }
+
+  // If the suggestion already has a favicon, we populate the element with it.
+  if (!mv_item.favicon.spec().empty()) {
+    obj->Set(v8::String::NewFromUtf8(isolate, "faviconUrl"),
+             UTF8ToV8String(isolate, mv_item.favicon.spec()));
+  }
+
   if (IsIconNTPEnabled()) {
     // Update website http://www.chromium.org/embeddedsearch when we make this
     // permanent.