chromeos: Disable SingleProcessMash when multi-process Mash is enabled

The two feature flags are incompatible, so make multi-process mash
take precedence.

Fix some direct references to features::kMash for consistency.

TBR=sky@chromium.org

Bug: 918859
Test: chrome --login-manager --enable-features=Mash logs in
Change-Id: I18ac68e5e7bd01962369549b2b966592b9db0105
Reviewed-on: https://chromium-review.googlesource.com/c/1394796
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619786}

ash/ash_service.cc

@@ -69,7 +69,7 @@ AshService::AshService(service_manager::mojom::ServiceRequest request)
     : service_binding_(this, std::move(request)) {}
 
 AshService::~AshService() {
-  if (!base::FeatureList::IsEnabled(features::kMash))
+  if (!::features::IsMultiProcessMash())
     return;
 
   // Shutdown part of GpuHost before deleting Shell. This is necessary to
@@ -175,7 +175,7 @@ void AshService::OnStart() {
   registry_.AddInterface(base::BindRepeating(&AshService::BindServiceFactory,
                                              base::Unretained(this)));
 
-  if (base::FeatureList::IsEnabled(features::kMash))
+  if (::features::IsMultiProcessMash())
     InitForMash();
 }
 
@@ -192,7 +192,7 @@ void AshService::CreateService(
     service_manager::mojom::PIDReceiverPtr pid_receiver) {
   DCHECK_EQ(name, ws::mojom::kServiceName);
   Shell::Get()->window_service_owner()->BindWindowService(std::move(service));
-  if (base::FeatureList::IsEnabled(features::kMash)) {
+  if (::features::IsMultiProcessMash()) {
     ws::WindowService* window_service =
         Shell::Get()->window_service_owner()->window_service();
     input_device_controller_ = std::make_unique<ws::InputDeviceController>();

ash/host/ash_window_tree_host_platform.cc

@@ -187,7 +187,7 @@ void AshWindowTreeHostPlatform::CommonInit() {
   event_queue_ =
       Shell::Get()->window_service_owner()->window_service()->event_queue();
 
-  if (!base::FeatureList::IsEnabled(features::kMash))
+  if (!::features::IsMultiProcessMash())
     return;
 
   input_method_ = std::make_unique<aura::InputMethodMus>(this, this);

ash/system/flag_warning/flag_warning_tray_unittest.cc

@@ -4,38 +4,30 @@
 
 #include "ash/system/flag_warning/flag_warning_tray.h"
 
-#include "ash/root_window_controller.h"
+#include "ash/public/cpp/shell_window_ids.h"
 #include "ash/shell.h"
 #include "ash/system/status_area_widget.h"
 #include "ash/test/ash_test_base.h"
-#include "base/macros.h"
 #include "base/test/scoped_feature_list.h"
 #include "ui/base/ui_base_features.h"
 
 namespace ash {
 namespace {
 
-class FlagWarningTrayTest : public AshTestBase {
- public:
-  FlagWarningTrayTest() = default;
-  ~FlagWarningTrayTest() override = default;
-
-  // testing::Test:
-  void SetUp() override {
-    scoped_feature_list_.InitAndEnableFeature(::features::kMash);
-    AshTestBase::SetUp();
-  }
-
- private:
-  base::test::ScopedFeatureList scoped_feature_list_;
-
-  DISALLOW_COPY_AND_ASSIGN(FlagWarningTrayTest);
-};
+using FlagWarningTrayTest = AshTestBase;
 
 TEST_F(FlagWarningTrayTest, VisibleForMash) {
-  FlagWarningTray* tray = Shell::GetPrimaryRootWindowController()
-                              ->GetStatusAreaWidget()
-                              ->flag_warning_tray_for_testing();
+  // Simulate enabling Mash.
+  base::test::ScopedFeatureList scoped_feature_list;
+  scoped_feature_list.InitWithFeatures(
+      {::features::kMash} /* enabled */,
+      {::features::kSingleProcessMash} /* disabled */);
+
+  StatusAreaWidget widget(Shell::GetContainer(Shell::GetPrimaryRootWindow(),
+                                              kShellWindowId_StatusContainer),
+                          GetPrimaryShelf());
+  widget.Initialize();
+  FlagWarningTray* tray = widget.flag_warning_tray_for_testing();
   ASSERT_TRUE(tray);
   EXPECT_TRUE(tray->visible());
 }

chrome/browser/ui/ash/chrome_browser_main_extra_parts_ash.cc

@@ -152,6 +152,9 @@ ChromeBrowserMainExtraPartsAsh::~ChromeBrowserMainExtraPartsAsh() {
 void ChromeBrowserMainExtraPartsAsh::ServiceManagerConnectionStarted(
     content::ServiceManagerConnection* connection) {
   if (features::IsMultiProcessMash()) {
+    // Mash and SingleProcessMash cannot be enabled simultaneously.
+    DCHECK(!features::IsSingleProcessMash());
+
     // ash::Shell will not be created because ash is running out-of-process.
     ash::Shell::SetIsBrowserProcessWithMash();
   }

ui/base/ui_base_features.cc

@@ -149,7 +149,8 @@ bool IsMashOopVizEnabled() {
 }
 
 bool IsSingleProcessMash() {
-  return base::FeatureList::IsEnabled(features::kSingleProcessMash);
+  return base::FeatureList::IsEnabled(features::kSingleProcessMash) &&
+         !base::FeatureList::IsEnabled(features::kMash);
 }
 
 bool IsAutomaticUiAdjustmentsForTouchEnabled() {

ui/base/ui_base_features.h

@@ -60,6 +60,8 @@ UI_BASE_EXPORT extern const base::Feature kMash;
 // make it the default kMash behavior.
 UI_BASE_EXPORT extern const base::Feature kMashOopViz;
 
+// NOTE: Do not access directly outside of tests. Use IsSingleProcessMash()
+// to avoid problems when Mash and SingleProcessMash are both enabled.
 UI_BASE_EXPORT extern const base::Feature kSingleProcessMash;
 
 // Returns true if Chrome's aura usage is backed by the WindowService.