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

chrome/browser/ui/search/search.cc

Index: chrome/browser/ui/search/search.cc
diff --git a/chrome/browser/ui/search/search.cc b/chrome/browser/ui/search/search.cc
index 796edb4ee64bf23013c73c455ea65b7d8c84b63d..4d89dbcba763bcd665cccc74694d32b29234d329 100644
--- a/chrome/browser/ui/search/search.cc
+++ b/chrome/browser/ui/search/search.cc
@@ -6,12 +6,14 @@
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
+#include "base/string16.h"

[sreeram, 2013/01/30 21:41:39]

Nit: No need for this (since it's already included in search.h).

[Mathieu, 2013/01/30 21:55:12]

Done.

 #include "base/string_number_conversions.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
+#include "content/public/browser/navigation_entry.h"
 
 #if !defined(OS_ANDROID)
 #include "chrome/browser/themes/theme_service.h"
@@ -46,6 +48,9 @@ const char kDisablingSuffix[] = "DISABLED";
 namespace chrome {
 namespace search {
 
+// static
+const char kInstantExtendedSearchTermsKey[] = "search_terms";
+
 // Check whether or not the Extended API should be used on the given profile.
 bool IsInstantExtendedAPIEnabled(Profile* profile) {
   return EmbeddedSearchPageVersion(profile) != 0;
@@ -139,6 +144,16 @@ void EnableQueryExtractionForTesting() {
 #endif
 }
 
+string16 GetSearchTermsFromNavigationEntry(
+    const content::NavigationEntry* entry) {
+  string16 out_value;
+  if (entry->GetExtraData(
+      std::string(kInstantExtendedSearchTermsKey),
+      &out_value))
+    return out_value;
+  return string16();

[sreeram, 2013/01/30 21:41:39]

Nit: If you rewrite this as the following, it will help the compiler perform
NRVO:
  string16 search_terms;
  if (!entry->GetExtraData(std::string(kInstantExtendedSearchTermsKey),
                           &search_terms))
    search_terms.clear();
  return search_terms;

In fact, I'd drop the 'if' check and std::string conversions and just do this:
  string16 search_terms;
  entry->GetExtraData(kInstantExtendedSearchTermsKey, &search_terms);
  return search_terms;

[Mathieu, 2013/01/30 21:55:12]

Done.

+}
+
 bool IsForcedInstantURL(const GURL& url) {
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   if (!command_line->HasSwitch(switches::kInstantURL))