[ozone/wayland] Use PlatformProperties to know if mojo is required.

Relying on OzoneDrmMojo feature is not a very good idea, because
it is mostly intended to be used with the Ozone/Drm platform, which can use both
the legacy IPC and mojo for communication. It happened once that the
Ozone/Wayland platform regressed due to misunderstandings why that
feature flag was used with ifdefs.

In Ozone/Wayland, the mojo IPC is a requirement to be able to run
the browser in a multi-process mode(there is a separate GPU process).
Thus, use PlatformProperties to know if the platform requires mojo communication
before the gpu is started. At the moment, only Ozone/Wayland
platform requires mojo communication in addition to the Ozone/Drm
platform, which can use both legacy IPC and mojo and uses OzoneDrmMojo
feature instead.

Bug: 578890
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I1f0fccb19ec2fc69a50320b55014979556739c2c
Reviewed-on: https://chromium-review.googlesource.com/c/1254209
Commit-Queue: Maksim Sisov <msisov@igalia.com>
Reviewed-by: Eric Karl <ericrk@chromium.org>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596174}

components/viz/host/gpu_host_impl.cc

@@ -293,7 +293,13 @@ void GpuHostImpl::InitOzone() {
   // https://crbug.com/608839
   // If the OzonePlatform is not created yet, defer the callback until
   // OzonePlatform instance is created.
-  if (features::IsOzoneDrmMojo()) {
+  //
+  // The Ozone/Wayland requires mojo communication to be established to be
+  // functional with a separate gpu process. Thus, using the PlatformProperties,
+  // check if there is such a requirement.
+  if (features::IsOzoneDrmMojo() || ui::OzonePlatform::EnsureInstance()
+                                        ->GetPlatformProperties()
+                                        .requires_mojo) {
     // TODO(rjkroege): Remove the legacy IPC code paths when no longer
     // necessary. https://crbug.com/806092
     auto interface_binder = base::BindRepeating(&GpuHostImpl::BindInterface,

gpu/ipc/service/gpu_init.cc

@@ -204,7 +204,10 @@ bool GpuInit::InitializeAndStartSandbox(base::CommandLine* command_line,
   // may also have started at this point.
   ui::OzonePlatform::InitParams params;
   params.single_process = false;
-  params.using_mojo = features::IsOzoneDrmMojo();
+  params.using_mojo =
+      features::IsOzoneDrmMojo() || ui::OzonePlatform::EnsureInstance()
+                                        ->GetPlatformProperties()
+                                        .requires_mojo;
   ui::OzonePlatform::InitializeForGPU(params);
 #endif
 
@@ -365,7 +368,10 @@ void GpuInit::InitializeInProcess(base::CommandLine* command_line,
 #if defined(USE_OZONE)
   ui::OzonePlatform::InitParams params;
   params.single_process = true;
-  params.using_mojo = features::IsOzoneDrmMojo();
+  params.using_mojo =
+      features::IsOzoneDrmMojo() || ui::OzonePlatform::EnsureInstance()
+                                        ->GetPlatformProperties()
+                                        .requires_mojo;
   ui::OzonePlatform::InitializeForGPU(params);
   ui::OzonePlatform::GetInstance()->AfterSandboxEntry();
 #endif

ui/ozone/platform/scenic/ozone_platform_scenic.cc

@@ -33,6 +33,7 @@ const OzonePlatform::PlatformProperties kScenicPlatformProperties(
     /*needs_view_owner_request=*/true,
     /*custom_frame_pref_default=*/false,
     /*use_system_title_bar=*/false,
+    /*requires_mojo=*/false,
     std::vector<gfx::BufferFormat>());
 
 class ScenicPlatformEventSource : public ui::PlatformEventSource {

ui/ozone/platform/wayland/ozone_platform_wayland.cc

@@ -52,6 +52,10 @@ class OzonePlatformWayland : public OzonePlatform {
     // https://github.com/wayland-project/wayland-protocols/commit/76d1ae8c65739eff3434ef219c58a913ad34e988
     properties_.custom_frame_pref_default = true;
     properties_.use_system_title_bar = false;
+    // Ozone/Wayland relies on the mojo communication when running in
+    // !single_process.
+    // TODO(msisov, rjkroege): Remove after http://crbug.com/806092.
+    properties_.requires_mojo = true;
   }
   ~OzonePlatformWayland() override {}
 
@@ -124,17 +128,8 @@ class OzonePlatformWayland : public OzonePlatform {
       LOG(FATAL) << "Failed to initialize Wayland platform";
 
 #if defined(WAYLAND_GBM)
-    if (!args.single_process) {
-      if (!features::IsOzoneDrmMojo()) {
-        // Override kEnableOzoneDrmMojo to the enabled state, because
-        // Ozone/Wayland relies on the mojo communication when running in
-        // !single_process.
-        // TODO(msisov, rjkroege): Remove after http://crbug.com/806092.
-        base::FeatureList::GetInstance()->InitializeFromCommandLine(
-            features::kEnableOzoneDrmMojo.name, std::string());
-      }
+    if (!args.single_process)
       connector_.reset(new WaylandConnectionConnector(connection_.get()));
-    }
 #endif
 
     cursor_factory_.reset(new BitmapCursorFactoryOzone);
@@ -169,8 +164,7 @@ class OzonePlatformWayland : public OzonePlatform {
   }
 
   const PlatformProperties& GetPlatformProperties() override {
-    DCHECK(connection_.get());
-    if (properties_.supported_buffer_formats.empty()) {
+    if (connection_ && properties_.supported_buffer_formats.empty()) {
       properties_.supported_buffer_formats =
           connection_->GetSupportedBufferFormats();
     }

ui/ozone/public/ozone_platform.cc

@@ -41,10 +41,12 @@ OzonePlatform::PlatformProperties::PlatformProperties(
     bool needs_request,
     bool custom_frame_default,
     bool can_use_system_title_bar,
+    bool requires_mojo_for_ipc,
     std::vector<gfx::BufferFormat> buffer_formats)
     : needs_view_owner_request(needs_request),
       custom_frame_pref_default(custom_frame_default),
       use_system_title_bar(can_use_system_title_bar),
+      requires_mojo(requires_mojo_for_ipc),
       supported_buffer_formats(buffer_formats) {}
 
 OzonePlatform::PlatformProperties::~PlatformProperties() = default;

ui/ozone/public/ozone_platform.h

@@ -91,6 +91,7 @@ class OZONE_EXPORT OzonePlatform {
     PlatformProperties(bool needs_request,
                        bool custom_frame_default,
                        bool can_use_system_title_bar,
+                       bool requires_mojo_for_ipc,
                        std::vector<gfx::BufferFormat> buffer_formats);
     ~PlatformProperties();
     PlatformProperties(const PlatformProperties& other);
@@ -108,6 +109,10 @@ class OZONE_EXPORT OzonePlatform {
     // supported.
     bool use_system_title_bar = false;
 
+    // Determines if the platform requires mojo communication for the IPC.
+    // Currently used only by the Ozone/Wayland platform.
+    bool requires_mojo = false;
+
     // Wayland only: carries buffer formats supported by a Wayland server.
     std::vector<gfx::BufferFormat> supported_buffer_formats;
   };