exo: Advertise bug fix IDs on binding zaura_shell

Currently, fixing exo bugs for Lacros is cumbersome due to version
skew between Lacros/ash. In a single CL, we ideally want to 1) land
an exo fix and 2) land a conditional workaround in Lacros until ash
is uprevved to actually include the exo fix (see the bug for a real
world example).

To remedy this, this CL introduces a new |bug_fix| event that sends
down IDs of bug fixes present in exo when the zaura_shell is bound.
Clients (notably |ui::WaylandZAuraShell|) can listen for this event
and gate features on the presence of certain bug fixes by calling
|WaylandZAuraShell::HasBugFix(bug_id)|.

Bug: 1151508
Change-Id: Iec39e32c4b507545aaf59c0a73f3fa61f9a7e3ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2568204
Commit-Queue: Brian Ho <hob@chromium.org>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837086}

components/exo/wayland/clients/client_base.cc

@@ -141,7 +141,7 @@ void RegistryHandler(void* data,
         wl_registry_bind(registry, id, &wp_presentation_interface, 1)));
   } else if (strcmp(interface, "zaura_shell") == 0) {
     globals->aura_shell.reset(static_cast<zaura_shell*>(
-        wl_registry_bind(registry, id, &zaura_shell_interface, 7)));
+        wl_registry_bind(registry, id, &zaura_shell_interface, 14)));
   } else if (strcmp(interface, "zwp_linux_dmabuf_v1") == 0) {
     globals->linux_dmabuf.reset(static_cast<zwp_linux_dmabuf_v1*>(
         wl_registry_bind(registry, id, &zwp_linux_dmabuf_v1_interface, 2)));
@@ -626,6 +626,15 @@ bool ClientBase::Init(const InitParams& params) {
       LOG(ERROR) << "Can't find aura shell interface";
       return false;
     }
+    static zaura_shell_listener kAuraShellListener = {
+        [](void* data, struct zaura_shell* zaura_shell, uint32_t layout_mode) {
+        },
+        [](void* data, struct zaura_shell* zaura_shell, uint32_t id) {
+          CastToClientBase(data)->bug_fix_ids_.insert(id);
+        }};
+    zaura_shell_add_listener(globals_.aura_shell.get(), &kAuraShellListener,
+                             this);
+
     std::unique_ptr<wl_shell_surface> shell_surface(
         static_cast<wl_shell_surface*>(
             wl_shell_get_shell_surface(globals_.shell.get(), surface_.get())));

components/exo/wayland/clients/client_base.h

@@ -9,6 +9,7 @@
 #include <string>
 #include <vector>
 
+#include "base/containers/flat_set.h"
 #include "base/memory/shared_memory_mapping.h"
 #include "components/exo/wayland/clients/client_helper.h"
 #include "third_party/skia/include/core/SkCanvas.h"
@@ -215,6 +216,7 @@ class ClientBase {
   unsigned egl_sync_type_ = 0;
   std::vector<std::unique_ptr<Buffer>> buffers_;
   sk_sp<GrDirectContext> gr_context_;
+  base::flat_set<uint32_t> bug_fix_ids_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ClientBase);

components/exo/wayland/clients/simple.cc

@@ -97,6 +97,10 @@ Simple::Simple() = default;
 void Simple::Run(int frames,
                  const bool log_vsync_timing_updates,
                  PresentationFeedback* feedback) {
+  wl_display_roundtrip(display_.get());
+  // We always send this bug fix ID as a sanity check.
+  DCHECK(bug_fix_ids_.find(1151508) != bug_fix_ids_.end());
+
   wl_callback_listener frame_listener = {FrameCallback};
   wp_presentation_feedback_listener feedback_listener = {
       FeedbackSyncOutput, FeedbackPresented, FeedbackDiscarded};

components/exo/wayland/protocol/aura-shell.xml

@@ -24,7 +24,7 @@
     DEALINGS IN THE SOFTWARE.
   </copyright>
 
-  <interface name="zaura_shell" version="12">
+  <interface name="zaura_shell" version="14">
     <description summary="aura_shell">
       The global interface exposing aura shell capabilities is used to
       instantiate an interface extension for a wl_surface object.
@@ -83,6 +83,16 @@
       </description>
       <arg name="layout_mode" type="uint" summary="layout_mode enum"/>
     </event>
+
+    <!-- Version 14 additions -->
+
+    <event name="bug_fix" since="14">
+      <description summary="sends a bug fix ID">
+        Sends a monorail ID of a bug fixed on the exo server that clients can
+        use to gate functionality.
+      </description>
+      <arg name="id" type="uint" summary="ID of a single bug fix"/>
+    </event>
   </interface>
 
   <interface name="zaura_surface" version="12">

components/exo/wayland/zaura_shell.cc

@@ -471,6 +471,14 @@ class AuraOutput : public WaylandDisplayObserver {
 // aura_shell_interface:
 
 #if BUILDFLAG(IS_CHROMEOS_ASH)
+
+// IDs of bugs that have been fixed in the exo implementation. These are
+// propagated to clients on aura_shell bind and can be used to gate client
+// logic on the presence of certain fixes.
+const uint32_t kFixedBugIds[] = {
+  1151508, // Do not remove, used for sanity checks by |wayland_simple_client|
+};
+
 // Implements aura shell interface and monitors workspace state needed
 // for the aura shell interface.
 class WaylandAuraShell : public ash::TabletModeObserver {
@@ -486,6 +494,12 @@ class WaylandAuraShell : public ash::TabletModeObserver {
                              : ZAURA_SHELL_LAYOUT_MODE_WINDOWED;
       zaura_shell_send_layout_mode(aura_shell_resource_, layout_mode);
     }
+    if (wl_resource_get_version(aura_shell_resource_) >=
+        ZAURA_SHELL_BUG_FIX_SINCE_VERSION) {
+      for (uint32_t bug_id : kFixedBugIds) {
+        zaura_shell_send_bug_fix(aura_shell_resource_, bug_id);
+      }
+    }
   }
   WaylandAuraShell(const WaylandAuraShell&) = delete;
   WaylandAuraShell& operator=(const WaylandAuraShell&) = delete;

components/exo/wayland/zaura_shell.h

@@ -17,7 +17,7 @@ struct wl_resource;
 namespace exo {
 namespace wayland {
 
-constexpr uint32_t kZAuraShellVersion = 12;
+constexpr uint32_t kZAuraShellVersion = 14;
 
 // Adds bindings to the Aura Shell. Normally this implies Ash on ChromeOS
 // builds. On non-ChromeOS builds the protocol provides access to Aura windowing

ui/ozone/platform/wayland/BUILD.gn

@@ -372,11 +372,13 @@ source_set("wayland_unittests") {
     "host/wayland_window_unittest.cc",
     "test/wayland_test.cc",
     "test/wayland_test.h",
+    "host/wayland_zaura_shell_unittest.cc",
   ]
 
   deps = [
     ":test_support",
     ":wayland",
+    "//components/exo/wayland/protocol:aura_shell_protocol",
     "//testing/gmock",
     "//testing/gtest",
     "//third_party/wayland:wayland_server",

ui/ozone/platform/wayland/host/wayland_connection.cc

@@ -53,7 +53,7 @@
 namespace ui {
 
 namespace {
-constexpr uint32_t kMaxAuraShellVersion = 11;
+constexpr uint32_t kMaxAuraShellVersion = 14;
 constexpr uint32_t kMaxCompositorVersion = 4;
 constexpr uint32_t kMaxCursorShapesVersion = 1;
 constexpr uint32_t kMaxGtkPrimarySelectionDeviceManagerVersion = 1;

ui/ozone/platform/wayland/host/wayland_zaura_shell.cc

@@ -21,12 +21,17 @@ WaylandZAuraShell::WaylandZAuraShell(zaura_shell* aura_shell,
 
   static const zaura_shell_listener zaura_shell_listener = {
       &WaylandZAuraShell::OnLayoutMode,
+      &WaylandZAuraShell::OnBugFix,
   };
   zaura_shell_add_listener(obj_.get(), &zaura_shell_listener, this);
 }
 
 WaylandZAuraShell::~WaylandZAuraShell() = default;
 
+bool WaylandZAuraShell::HasBugFix(uint32_t id) {
+  return bug_fix_ids_.find(id) != bug_fix_ids_.end();
+}
+
 // static
 void WaylandZAuraShell::OnLayoutMode(void* data,
                                      struct zaura_shell* zaura_shell,
@@ -47,4 +52,12 @@ void WaylandZAuraShell::OnLayoutMode(void* data,
   }
 }
 
+// static
+void WaylandZAuraShell::OnBugFix(void* data,
+                                 struct zaura_shell* zaura_shell,
+                                 uint32_t id) {
+  auto* self = static_cast<WaylandZAuraShell*>(data);
+  self->bug_fix_ids_.insert(id);
+}
+
 }  // namespace ui

ui/ozone/platform/wayland/host/wayland_zaura_shell.h

@@ -5,6 +5,9 @@
 #ifndef UI_OZONE_PLATFORM_WAYLAND_HOST_WAYLAND_ZAURA_SHELL_H_
 #define UI_OZONE_PLATFORM_WAYLAND_HOST_WAYLAND_ZAURA_SHELL_H_
 
+#include <string>
+
+#include "base/containers/flat_set.h"
 #include "ui/ozone/platform/wayland/common/wayland_object.h"
 
 namespace ui {
@@ -20,15 +23,24 @@ class WaylandZAuraShell {
   ~WaylandZAuraShell();
 
   zaura_shell* wl_object() const { return obj_.get(); }
+  // Due to version skew between Lacros and Ash, there may be certain bug
+  // fixes in one but not in the other (crbug.com/1151508). Lacros can use
+  // |HasBugFix| to provide a temporary workaround to an exo bug until Ash
+  // uprevs and starts reporting that a given bug ID has been fixed.
+  bool HasBugFix(uint32_t id);
 
  private:
-  // zaura_shell_listener
+  // zaura_shell_listeners
   static void OnLayoutMode(void* data,
                            struct zaura_shell* zaura_shell,
                            uint32_t layout_mode);
+  static void OnBugFix(void* data,
+                       struct zaura_shell* zaura_shell,
+                       uint32_t id);
 
   wl::Object<zaura_shell> obj_;
   WaylandConnection* const connection_;
+  base::flat_set<uint32_t> bug_fix_ids_;
 };
 
 }  // namespace ui

ui/ozone/platform/wayland/host/wayland_zaura_shell_unittest.cc

+// Copyright 2020 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 <aura-shell-server-protocol.h>
+
+#include "base/run_loop.h"
+#include "base/test/task_environment.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/ozone/platform/wayland/host/wayland_connection.h"
+#include "ui/ozone/platform/wayland/host/wayland_event_source.h"
+#include "ui/ozone/platform/wayland/host/wayland_zaura_shell.h"
+#include "ui/ozone/platform/wayland/test/global_object.h"
+#include "ui/ozone/platform/wayland/test/test_wayland_server_thread.h"
+
+namespace ui {
+
+namespace {
+
+constexpr uint32_t kXdgVersionStable = 7;
+constexpr uint32_t kZAuraShellVersion = 14;
+
+}  // namespace
+
+TEST(WaylandZauraShellTest, Foo) {
+  base::test::SingleThreadTaskEnvironment task_environment(
+      base::test::SingleThreadTaskEnvironment::MainThreadType::UI);
+  wl::TestWaylandServerThread server;
+  ASSERT_TRUE(server.Start(kXdgVersionStable));
+  wl::GlobalObject zaura_shell_obj(
+      &zaura_shell_interface, nullptr /* implementation */, kZAuraShellVersion);
+  zaura_shell_obj.Initialize(server.display());
+
+  WaylandConnection connection;
+  ASSERT_TRUE(connection.Initialize());
+  connection.event_source()->StartProcessingEvents();
+
+  base::RunLoop().RunUntilIdle();
+  server.Pause();
+
+  zaura_shell_send_bug_fix(zaura_shell_obj.resource(), 1);
+  zaura_shell_send_bug_fix(zaura_shell_obj.resource(), 3);
+
+  server.Resume();
+  base::RunLoop().RunUntilIdle();
+  server.Pause();
+
+  ASSERT_TRUE(connection.zaura_shell()->HasBugFix(1));
+  ASSERT_TRUE(connection.zaura_shell()->HasBugFix(3));
+  ASSERT_FALSE(connection.zaura_shell()->HasBugFix(2));
+}
+
+}  // namespace ui