OptimizationGuide: Put feature flag helpers into `features` namespace

This is a follow-up CL for the previous review comment:
https://chromium-review.googlesource.com/c/chromium/src/+/2389380/comment/65b648df_f6299bcf/

Bug: 1112515
Change-Id: Ia7ba8b79cb0b60567616773c8240c4c5b446e8aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2397992Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804938}

chrome/browser/optimization_guide/blink/blink_optimization_guide_feature_flag_helper.cc

@@ -8,6 +8,7 @@
 #include "third_party/blink/public/common/features.h"
 
 namespace optimization_guide {
+namespace features {
 
 bool ShouldUseOptimizationGuideForDelayAsyncScript() {
   static const bool is_feature_enabled =
@@ -28,4 +29,5 @@ bool ShouldUseOptimizationGuideForDelayCompetingLowPriorityRequests() {
   return is_feature_enabled;
 }
 
+}  // namespace features
 }  // namespace optimization_guide

chrome/browser/optimization_guide/blink/blink_optimization_guide_feature_flag_helper.h

@@ -6,11 +6,13 @@
 #define CHROME_BROWSER_OPTIMIZATION_GUIDE_BLINK_BLINK_OPTIMIZATION_GUIDE_FEATURE_FLAG_HELPER_H_
 
 namespace optimization_guide {
+namespace features {
 
 bool ShouldUseOptimizationGuideForDelayAsyncScript();
 
 bool ShouldUseOptimizationGuideForDelayCompetingLowPriorityRequests();
 
+}  // namespace features
 }  // namespace optimization_guide
 
 #endif  // CHROME_BROWSER_OPTIMIZATION_GUIDE_BLINK_BLINK_OPTIMIZATION_GUIDE_FEATURE_FLAG_HELPER_H_

chrome/browser/optimization_guide/blink/blink_optimization_guide_inquirer.cc

@@ -38,11 +38,12 @@ void BlinkOptimizationGuideInquirer::InquireHints(
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   std::vector<proto::OptimizationType> supported_optimization_types;
-  if (ShouldUseOptimizationGuideForDelayAsyncScript()) {
+  if (features::ShouldUseOptimizationGuideForDelayAsyncScript()) {
     supported_optimization_types.push_back(
         proto::OptimizationType::DELAY_ASYNC_SCRIPT_EXECUTION);
   }
-  if (ShouldUseOptimizationGuideForDelayCompetingLowPriorityRequests()) {
+  if (features::
+          ShouldUseOptimizationGuideForDelayCompetingLowPriorityRequests()) {
     supported_optimization_types.push_back(
         proto::OptimizationType::DELAY_COMPETING_LOW_PRIORITY_REQUESTS);
   }

chrome/browser/optimization_guide/blink/blink_optimization_guide_web_contents_observer.cc

@@ -88,9 +88,10 @@ BlinkOptimizationGuideWebContentsObserver::
 
   // Register the optimization types which we want to subscribe to.
   std::vector<proto::OptimizationType> opts;
-  if (ShouldUseOptimizationGuideForDelayAsyncScript())
+  if (features::ShouldUseOptimizationGuideForDelayAsyncScript())
     opts.push_back(proto::OptimizationType::DELAY_ASYNC_SCRIPT_EXECUTION);
-  if (ShouldUseOptimizationGuideForDelayCompetingLowPriorityRequests()) {
+  if (features::
+          ShouldUseOptimizationGuideForDelayCompetingLowPriorityRequests()) {
     opts.push_back(
         proto::OptimizationType::DELAY_COMPETING_LOW_PRIORITY_REQUESTS);
   }