Implement the Windows desktop search redirection feature.

components/search_engines/desktop_search_utils.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/search_engines/desktop_search_utils.h"
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/metrics/user_metrics.h"
+#include "base/prefs/pref_service.h"
+#include "base/strings/string_util.h"
+#include "components/pref_registry/pref_registry_syncable.h"
+#include "components/search_engines/prepopulated_engines.h"
+#include "components/search_engines/template_url_prepopulate_data.h"
+#include "components/search_engines/template_url_service.h"
+#include "components/search_engines/util.h"
+#include "net/base/url_util.h"
+
+namespace prefs {
+const char kDesktopSearchRedirectionInfobarShownPref[] =
+    "desktop_search_redirection_infobar_shown";
+}  // namespace prefs
+
+const base::Feature kDesktopSearchRedirectionFeature{
+    "DesktopSearchRedirection", base::FEATURE_DISABLED_BY_DEFAULT};
+
+namespace {

[Peter Kasting, 2016/01/22 00:38:57]

Nit: Put anonymous namespace stuff just below the #includes, above any other
namespaces/declarations

[fdoray, 2016/02/01 15:15:53]

Done.

+
+// Values for the Search.DesktopSearch.URLAction histogram.
+enum DesktopSearchURLAction {
+  DESKTOP_SEARCH_URL_ACTION_NO_REDIRECTION_FEATURE_DISABLED = 0,
+  DESKTOP_SEARCH_URL_ACTION_NO_REDIRECTION_DEFAULT_SEARCH_IS_BING = 1,
+  DESKTOP_SEARCH_URL_ACTION_NO_REDIRECTION_INVALID_SEARCH_ENGINE = 2,
+  DESKTOP_SEARCH_URL_ACTION_REDIRECTION = 3,
+  DESKTOP_SEARCH_URL_ACTION_MAX
+};
+
+void RecordDesktopSearchURLAction(DesktopSearchURLAction action) {
+  DCHECK_LT(action, DESKTOP_SEARCH_URL_ACTION_MAX);
+  UMA_HISTOGRAM_ENUMERATION("Search.DesktopSearch.URLAction", action,
+                            DESKTOP_SEARCH_URL_ACTION_MAX);
+}
+
+// Detects whether a |url| comes from a desktop search. If so, puts the search
+// terms in |search_terms| and returns true.
+bool DetectDesktopSearch(const GURL& url,
+                         const SearchTermsData& search_terms_data,
+                         base::string16* search_terms) {
+  DCHECK(search_terms);
+  search_terms->clear();
+
+  scoped_ptr<TemplateURLData> template_url_data =
+      TemplateURLPrepopulateData::MakeTemplateURLDataFromPrepopulatedEngine(
+          TemplateURLPrepopulateData::bing);
+  TemplateURL template_url(*template_url_data);
+  if (!template_url.ExtractSearchTermsFromURL(url, search_terms_data,
+                                              search_terms))
+    return false;
+
+  // Query parameter that tells the source of a Bing search URL, and values
+  // associated with desktop search.
+  const char kBingSourceQueryKey[] = "form";
+  const char kBingSourceDesktopText[] = "WNSGPH";
+  const char kBingSourceDesktopVoice[] = "WNSBOX";
+  for (net::QueryIterator it(url); !it.IsAtEnd(); it.Advance()) {
+    // Use a case-insensitive comparison because the key is sometimes in capital
+    // letters.
+    if (base::EqualsCaseInsensitiveASCII(it.GetKey(), kBingSourceQueryKey)) {
+      const std::string source = it.GetValue();
+      if (source == kBingSourceDesktopText || source == kBingSourceDesktopVoice)
+        return true;
+    }
+  }
+
+  return false;
+}
+
+}  // namespace
+
+void RegisterDesktopSearchRedirectionPref(
+    user_prefs::PrefRegistrySyncable* registry) {
+  registry->RegisterBooleanPref(
+      prefs::kDesktopSearchRedirectionInfobarShownPref, false);
+}
+
+bool ReplaceDesktopSearchURLWithDefaultSearchURLIfNeeded(
+    const PrefService* pref_service,
+    TemplateURLService* template_url_service,
+    GURL* url) {
+  DCHECK(pref_service);
+  DCHECK(template_url_service);
+  DCHECK(url);
+
+  // Check if |url| is a desktop search.
+  base::string16 search_terms;
+  if (!DetectDesktopSearch(*url, template_url_service->search_terms_data(),
+                           &search_terms))
+    return false;
+
+  // Record that the user searched from the desktop.
+  base::RecordAction(base::UserMetricsAction("DesktopSearch"));
+
+  // Check if the redirection feature is enabled.
+  if (!base::FeatureList::IsEnabled(kDesktopSearchRedirectionFeature)) {
+    RecordDesktopSearchURLAction(
+        DESKTOP_SEARCH_URL_ACTION_NO_REDIRECTION_FEATURE_DISABLED);
+    return false;
+  }
+
+  const TemplateURL* default_search_engine =

[Peter Kasting, 2016/01/22 00:38:57]

Nit: Put this block just below the next comment since it's closely associated
with checking what the default search engine is.

[fdoray, 2016/02/01 15:15:53]

Done.

+      template_url_service->GetDefaultSearchProvider();
+  DCHECK(default_search_engine);

[Peter Kasting, 2016/01/22 00:38:57]

It's not safe to DCHECK this; users may not have a DSE.  Instead, make sure this
case returns false (and probably records an INVALID_SEARCH_ENGINE action).

[fdoray, 2016/02/01 15:15:53]

Done.

+
+  // Check if the default search engine is Bing.
+  if (TemplateURLPrepopulateData::GetEngineType(
+          *default_search_engine, template_url_service->search_terms_data()) ==
+      SEARCH_ENGINE_BING) {
+    RecordDesktopSearchURLAction(
+        DESKTOP_SEARCH_URL_ACTION_NO_REDIRECTION_DEFAULT_SEARCH_IS_BING);
+    return false;
+  }
+
+  // Replace |url| by a default search engine URL.
+  GURL search_url(
+      GetDefaultSearchURLForSearchTerms(template_url_service, search_terms));
+  if (!search_url.is_valid()) {
+    RecordDesktopSearchURLAction(
+        DESKTOP_SEARCH_URL_ACTION_NO_REDIRECTION_INVALID_SEARCH_ENGINE);
+    return false;
+  }
+
+  RecordDesktopSearchURLAction(DESKTOP_SEARCH_URL_ACTION_REDIRECTION);
+
+  url->Swap(&search_url);
+  return !pref_service->GetBoolean(
+      prefs::kDesktopSearchRedirectionInfobarShownPref);
+}