[Search] Store and recall search terms using NavigationEntry to improve search term extraction

chrome/browser/ui/toolbar/toolbar_model_impl.cc

Index: chrome/browser/ui/toolbar/toolbar_model_impl.cc
diff --git a/chrome/browser/ui/toolbar/toolbar_model_impl.cc b/chrome/browser/ui/toolbar/toolbar_model_impl.cc
index 1d20fa01495539b225dd6be8e8abb57730a8a069..e36b1af4a404d6e9bfac1f836a48c69a0d24d3c4 100644
--- a/chrome/browser/ui/toolbar/toolbar_model_impl.cc
+++ b/chrome/browser/ui/toolbar/toolbar_model_impl.cc
@@ -8,6 +8,7 @@
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/autocomplete/autocomplete_input.h"
 #include "chrome/browser/google/google_util.h"
+#include "chrome/browser/instant/instant_controller.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search_engines/template_url.h"
@@ -72,6 +73,10 @@ ToolbarModelImpl::~ToolbarModelImpl() {
 string16 ToolbarModelImpl::GetText(
     bool display_search_urls_as_search_terms) const {
   if (display_search_urls_as_search_terms) {
+    // If search terms were set explicitly on the NavigationEntry, use those.
+    string16 entry_search_terms = GetSearchTermsFromNavigationEntry();
+    if (!entry_search_terms.empty())
+      return entry_search_terms;
     string16 search_terms = TryToExtractSearchTermsFromURL();
     if (!search_terms.empty())
       return search_terms;
@@ -107,6 +112,21 @@ bool ToolbarModelImpl::WouldReplaceSearchURLWithSearchTerms() const {
   return !TryToExtractSearchTermsFromURL().empty();
 }
 
+string16 ToolbarModelImpl::GetSearchTermsFromNavigationEntry() const {
+  NavigationController* controller = GetNavigationController();
+  if (controller) {
+    NavigationEntry* entry = controller->GetVisibleEntry();
+    if (entry) {
+      string16 out_value;
+      if (entry->GetExtraData(
+          std::string(InstantController::kInstantExtendedSearchTermsKey),
+          &out_value))
+        return out_value;
+    }
+  }
+  return string16();
+}
+
 bool ToolbarModelImpl::ShouldDisplayURL() const {
   // Note: The order here is important.
   // - The WebUI test must come before the extension scheme test because there