[Icons NTP] Use GetVariationParamValue instead of experiment prefix to...

[Icons NTP] Use GetVariationParamValue instead of experiment prefix to determine when large icons are enabled.

This is the standard pattern for adding a forcing flags in about://flags.

This also matches a google3 change that just landed which declares that parameter.

BUG=467712

Review URL: https://codereview.chromium.org/1032073003

Cr-Commit-Position: refs/heads/master@{#322456}

chrome/browser/favicon/favicon_tab_helper.cc

@@ -4,7 +4,6 @@
 
 #include "chrome/browser/favicon/favicon_tab_helper.h"
 
-#include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/favicon/chrome_favicon_client.h"
@@ -21,6 +20,7 @@
 #include "components/favicon/core/favicon_tab_helper_observer.h"
 #include "components/favicon_base/favicon_types.h"
 #include "components/history/core/browser/history_service.h"
+#include "components/variations/variations_associated_data.h"
 #include "content/public/browser/favicon_status.h"
 #include "content/public/browser/invalidate_type.h"
 #include "content/public/browser/navigation_controller.h"
@@ -47,8 +47,7 @@ namespace {
 
 // Returns whether icon NTP is enabled.
 bool IsIconNTPEnabled() {
-  return StartsWithASCII(base::FieldTrialList::FindFullName("IconNTP"),
-                         "Enabled", true);
+  return variations::GetVariationParamValue("IconNTP", "state") == "enabled";
 }
 
 }  // namespace

chrome/browser/search/local_ntp_source.cc

@@ -20,6 +20,7 @@
 #include "chrome/grit/generated_resources.h"
 #include "components/search_engines/template_url_prepopulate_data.h"
 #include "components/search_engines/template_url_service.h"
+#include "components/variations/variations_associated_data.h"
 #include "grit/browser_resources.h"
 #include "grit/theme_resources.h"
 #include "net/url_request/url_request.h"
@@ -81,8 +82,7 @@ bool DefaultSearchProviderIsGoogle(Profile* profile) {
 
 // Returns whether icon NTP is enabled.
 bool IsIconNTPEnabled() {
-  return StartsWithASCII(base::FieldTrialList::FindFullName("IconNTP"),
-                         "Enabled", true);
+  return variations::GetVariationParamValue("IconNTP", "state") == "enabled";
 }
 
 // Returns whether we are in the Fast NTP experiment or not.

chrome/renderer/searchbox/searchbox_extension.cc

@@ -6,7 +6,6 @@
 
 #include "base/i18n/rtl.h"
 #include "base/json/string_escape.h"
-#include "base/metrics/field_trial.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
@@ -17,6 +16,7 @@
 #include "chrome/grit/renderer_resources.h"
 #include "chrome/renderer/searchbox/searchbox.h"
 #include "components/crx_file/id_util.h"
+#include "components/variations/variations_associated_data.h"
 #include "content/public/renderer/render_view.h"
 #include "third_party/WebKit/public/platform/WebURLRequest.h"
 #include "third_party/WebKit/public/web/WebDocument.h"
@@ -64,8 +64,7 @@ base::string16 V8ValueToUTF16(v8::Handle<v8::Value> v) {
 
 // Returns whether we should use large icons on NTP.
 bool IsIconNTPEnabled() {
-  return StartsWithASCII(base::FieldTrialList::FindFullName("IconNTP"),
-                         "Enabled", true);
+  return variations::GetVariationParamValue("IconNTP", "state") == "enabled";
 }
 
 // Converts string16 to V8 String.