Convert the overlay scrollbar flag to use FeatureList

content/browser/site_per_process_browsertest.cc

 // Copyright (c) 2012 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 "content/browser/site_per_process_browsertest.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
+#include "base/feature_list.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
 #include "base/path_service.h"
 #include "base/sequenced_task_runner.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/pattern.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/test_timeouts.h"
 #include "base/threading/sequenced_task_runner_handle.h"
@@ skipping 52 matching lines @@
 #include "third_party/WebKit/public/platform/WebInputEvent.h"
 #include "third_party/WebKit/public/platform/WebInsecureRequestPolicy.h"
 #include "third_party/WebKit/public/web/WebSandboxFlags.h"
 #include "ui/display/display_switches.h"
 #include "ui/display/screen.h"
 #include "ui/events/base_event_utils.h"
 #include "ui/events/event.h"
 #include "ui/events/event_utils.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/latency/latency_info.h"
-#include "ui/native_theme/native_theme_switches.h"
+#include "ui/native_theme/native_theme_features.h"
 
 #if defined(USE_AURA)
 #include "content/browser/renderer_host/render_widget_host_view_aura.h"
 #endif
 
 #if defined(OS_MACOSX)
 #include "ui/base/test/scoped_preferred_scroller_style_mac.h"
 #endif
 
 #if defined(OS_ANDROID)
@@ skipping 511 matching lines @@
 SitePerProcessBrowserTest::SitePerProcessBrowserTest() {
 };
 
 std::string SitePerProcessBrowserTest::DepictFrameTree(FrameTreeNode* node) {
   return visualizer_.DepictFrameTree(node);
 }
 
 void SitePerProcessBrowserTest::SetUpCommandLine(
     base::CommandLine* command_line) {
   IsolateAllSitesForTesting(command_line);
+}
+
+void SitePerProcessBrowserTest::SetUpOnMainThread() {
 #if !defined(OS_ANDROID)
   // TODO(bokan): Needed for scrollability check in
   // FrameOwnerPropertiesPropagationScrolling. crbug.com/662196.
-  command_line->AppendSwitch(switches::kDisableOverlayScrollbar);
+  base::FeatureList* existing_feature_list = base::FeatureList::GetInstance();
+  if (existing_feature_list) {
+    std::string enabled_features;
+    std::string disabled_features;
+    base::FeatureList::GetInstance()->GetFeatureOverrides(&enabled_features,
+                                                          &disabled_features);
+    disabled_features += "," + std::string(features::kOverlayScrollbar.name);

[dtapuska, 2017/04/12 17:21:02]

How do you know disable_features actually has anything?

Would it make more sense to follow code like:
https://cs.chromium.org/chromium/src/components/subresource_filter/core/brows...

Where it initializes the scoped feature list from a feature list?

[chaopeng, 2017/04/12 20:23:15]

Can not make this work as the link.

+    feature_list_.InitFromCommandLine(enabled_features, disabled_features);
+  } else {
+    feature_list_.InitAndDisableFeature(features::kOverlayScrollbar);
+  }
 #endif
-};
 
-void SitePerProcessBrowserTest::SetUpOnMainThread() {
   host_resolver()->AddRule("*", "127.0.0.1");
   SetupCrossSiteRedirector(embedded_test_server());
   ASSERT_TRUE(embedded_test_server()->Start());
 }
 
 //
 // SitePerProcessHighDPIBrowserTest
 //
 
 
@@ skipping 9221 matching lines @@
     names.insert(root->children[0]->frame_entry->frame_unique_name());
   }
 
   // More than one entry in the set means that the subframe frame navigation
   // entries didn't have a consistent unique name. This will break history
   // navigations =(
   EXPECT_THAT(names, SizeIs(1)) << "Mismatched names for subframe!";
 }
 
 }  // namespace content