Prefetch high-confidence search suggestions in Android Chrome.

chrome/browser/android/omnibox/autocomplete_controller_android.cc

Index: chrome/browser/android/omnibox/autocomplete_controller_android.cc
diff --git a/chrome/browser/android/omnibox/autocomplete_controller_android.cc b/chrome/browser/android/omnibox/autocomplete_controller_android.cc
index ea6cfc703780f4cf852d2ec56594f7edeb718f93..0966358a197e26d7cb673a41733723d971fc016f 100644
--- a/chrome/browser/android/omnibox/autocomplete_controller_android.cc
+++ b/chrome/browser/android/omnibox/autocomplete_controller_android.cc
@@ -16,6 +16,7 @@
 #include "chrome/browser/autocomplete/autocomplete_controller.h"
 #include "chrome/browser/autocomplete/autocomplete_input.h"
 #include "chrome/browser/autocomplete/autocomplete_match.h"
+#include "chrome/browser/autocomplete/search_provider.h"
 #include "chrome/browser/autocomplete/shortcuts_backend_factory.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ -24,11 +25,14 @@
 #include "chrome/browser/profiles/incognito_helpers.h"
 #include "chrome/browser/profiles/profile_android.h"
 #include "chrome/browser/profiles/profile_manager.h"
+#include "chrome/browser/search/search.h"
 #include "chrome/browser/search_engines/template_url_service.h"
 #include "chrome/browser/search_engines/template_url_service_factory.h"
 #include "chrome/browser/sessions/session_id.h"
+#include "chrome/browser/ui/search/instant_search_prerenderer.h"
 #include "chrome/browser/ui/toolbar/toolbar_model.h"
 #include "chrome/common/autocomplete_match_type.h"
+#include "chrome/common/instant_types.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
@@ -329,6 +333,28 @@ void AutocompleteControllerAndroid::InitJNI(JNIEnv* env, jobject obj) {
 
 void AutocompleteControllerAndroid::OnResultChanged(
     bool default_match_changed) {
+  if (default_match_changed &&

[Jered, 2014/06/13 16:53:20]

AutocompleteController::OnResultChanged() does not prerender if the autocomplete
result set is empty, but this method does. Is that behavior difference
intentional or should it be the same in both places?
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/ui/...

[kmadhusu, 2014/06/13 17:42:13]

It wasn't intentional. Updated the code to look the same in both places. Good
catch.

+      chrome::IsInstantExtendedAPIEnabled() &&
+      chrome::ShouldPrefetchSearchResults()) {
+    InstantSuggestion prefetch_suggestion;
+    const AutocompleteResult& result = autocomplete_controller_->result();
+    // If the default match should be prefetched, do that.
+    const AutocompleteResult::const_iterator default_match(
+        result.default_match());
+    if ((default_match != result.end()) &&
+        SearchProvider::ShouldPrefetch(*default_match)) {
+      prefetch_suggestion.text = default_match->contents;
+      prefetch_suggestion.metadata =
+          SearchProvider::GetSuggestMetadata(*default_match);
+    }
+    // Send the prefetch suggestion unconditionally to the Instant search base
+    // page. If there is no suggestion to prefetch, we need to send a blank
+    // query to clear the prefetched results.
+    InstantSearchPrerenderer* prerenderer =
+        InstantSearchPrerenderer::GetForProfile(profile_);
+    if (prerenderer)
+      prerenderer->Prerender(prefetch_suggestion);
+  }
   if (autocomplete_controller_.get() != NULL && !inside_synchronous_start_)
     NotifySuggestionsReceived(autocomplete_controller_->result());
 }