Remove search::ShouldPrefetchSearchResultsOnSRP

chrome/browser/ui/omnibox/chrome_omnibox_client.cc

Index: chrome/browser/ui/omnibox/chrome_omnibox_client.cc
diff --git a/chrome/browser/ui/omnibox/chrome_omnibox_client.cc b/chrome/browser/ui/omnibox/chrome_omnibox_client.cc
index e534939f83ca69a5497232d7daf75a1f035d7180..91d9bb206e82f56955bd953ddded2d31202ed79f 100644
--- a/chrome/browser/ui/omnibox/chrome_omnibox_client.cc
+++ b/chrome/browser/ui/omnibox/chrome_omnibox_client.cc
@@ -458,13 +458,8 @@ void ChromeOmniboxClient::SetSuggestionToPrefetch(
       const InstantSuggestion& suggestion) {
   DCHECK(search::IsInstantExtendedAPIEnabled());
   content::WebContents* web_contents = controller_->GetWebContents();
-  if (web_contents &&
-      SearchTabHelper::FromWebContents(web_contents)->IsSearchResultsPage()) {
-    if (search::ShouldPrefetchSearchResultsOnSRP()) {
-      SearchTabHelper::FromWebContents(web_contents)->
-          SetSuggestionToPrefetch(suggestion);
-    }
-  } else {
+  if (!web_contents ||

[Marc Treib, 2016/07/13 12:27:38]

This looks weird, but it preserves the previous behavior.

[Jered, 2016/07/19 14:03:27]

I am confused about what happened to this code.
1) It's often rather nice to have a server-settable flag to turn off prefetch,
in case say you accidentally ship a client that DoS'es your search engine
(oops). We appear to have removed such a flag already, below.
2) Prefetching search results on a SRP that is already loaded should be strictly
better for users than blowing it away and navigating to an entirely new SRP. I
wonder what happened to this trial?

Anyway I agree this is semantically equivalent, if bizarre. (I don't understand
why we'd not prefetch results only on a tab navigated to a results page.)

[Marc Treib, 2016/07/19 15:51:18]

Hah, I think I found it: The check used to be
"ShouldPrefetchSearchResults() || ShouldPrefetchSearchResultsOnSRP()"
Then, https://codereview.chromium.org/360373006 removed the
ShouldPrefetchSearchResults() check - supposedly by always enabling it, but it
left the "ShouldPrefetchSearchResultsOnSRP()" check there.
So, I'm *guessing* that the intended behavior is (or was):
if (SRP) SetSuggestionToPrefetch();
else Prerender();

Kausalya, can you comment on that?

+      !SearchTabHelper::FromWebContents(web_contents)->IsSearchResultsPage()) {
     InstantSearchPrerenderer* prerenderer =
         InstantSearchPrerenderer::GetForProfile(profile_);
     if (prerenderer)