wayland: xdg-session-management: Add command for platform_session_id

Some platforms support window-related session management at display
server side. Such as, Linux/Wayland with xdg-session-management protocol
extension. In that case, 1 new piece of data must be requested and
persisted by the client application in order to be able to ask the
windowing system to restore window states when needed:

- platform_session_id: a string that identifies a platform session,
  generated by the display server (eg: the Wayland compositor
  implementing the xdg-session-management protocol), stored by chromium
  in the session commands backing storage, and sent back to the display
  server when restoring a browser session.

Further design notes available at
https://notes.nickdiego.dev/chromium/wayland-session-management

The upcoming CLs will add the remaining bits, including:

- UI/Views framework API required additions.
- Ozone/Wayland implementation based on xdg-toplevel-drag-v1 protocol.
- Chrome required plumbing and required changes.

Bug: 352081012
Change-Id: I5d2d7c5755c1cf5848bffd6231cc75f3fda2def3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6329136
Reviewed-by: Darryl James <dljames@chromium.org>
Commit-Queue: Nick Yamane <nickdiego@igalia.com>
Cr-Commit-Position: refs/heads/main@{#1437661}

components/sessions/core/base_session_service_commands.cc

@@ -165,6 +165,19 @@ std::unique_ptr<SessionCommand> CreateAddExtraDataCommand(
   return std::make_unique<SessionCommand>(command, pickle);
 }
 
+std::unique_ptr<SessionCommand> CreateSetPlatformSessionIdCommand(
+    SessionCommand::id_type command_id,
+    const std::string& platform_session_id) {
+  base::Pickle pickle;
+  static const SessionCommand::size_type max_id_size =
+      std::numeric_limits<SessionCommand::size_type>::max() - 1024;
+  int bytes_written = 0;
+
+  WriteStringToPickle(pickle, &bytes_written, max_id_size, platform_session_id);
+
+  return std::make_unique<SessionCommand>(command_id, pickle);
+}
+
 bool RestoreUpdateTabNavigationCommand(
     const SessionCommand& command,
     sessions::SerializedNavigationEntry* navigation,
@@ -260,4 +273,12 @@ bool RestoreAddExtraDataCommand(const SessionCommand& command,
          it.ReadString(data);
 }
 
+bool RestoreSetPlatformSessionIdCommand(const SessionCommand& command,
+                                        std::string* platform_session_id) {
+  base::Pickle pickle = command.PayloadAsPickle();
+  base::PickleIterator iterator(pickle);
+
+  return iterator.ReadString(platform_session_id);
+}
+
 }  // namespace sessions

components/sessions/core/base_session_service_commands.h

@@ -59,6 +59,11 @@ std::unique_ptr<SessionCommand> CreateAddExtraDataCommand(
     const std::string& key,
     const std::string& data);
 
+// Creates a SessionCommand storing the platform session id.
+std::unique_ptr<SessionCommand> CreateSetPlatformSessionIdCommand(
+    SessionCommand::id_type command_id,
+    const std::string& platform_session_id);
+
 // Converts a SessionCommand previously created by
 // CreateUpdateTabNavigationCommand into a
 // SerializedNavigationEntry. Returns true on success. If
@@ -109,6 +114,11 @@ bool RestoreAddExtraDataCommand(const SessionCommand& command,
                                 std::string* key,
                                 std::string* data);
 
+// Extracts a SessionCommand as previously created by
+// CreateSetPlatformSessionIdCommand into platform_session_id.
+bool RestoreSetPlatformSessionIdCommand(const SessionCommand& command,
+                                        std::string* platform_session_id);
+
 }  // namespace sessions
 
 #endif  // COMPONENTS_SESSIONS_CORE_BASE_SESSION_SERVICE_COMMANDS_H_

components/sessions/core/session_service_commands.cc

@@ -80,6 +80,7 @@ static const SessionCommand::id_type kCommandSetWindowVisibleOnAllWorkspaces =
     32;
 static const SessionCommand::id_type kCommandAddTabExtraData = 33;
 static const SessionCommand::id_type kCommandAddWindowExtraData = 34;
+static const SessionCommand::id_type kCommandSetPlatformSessionId = 35;
 // ID 255 is used by CommandStorageBackend.
 
 namespace {
@@ -452,7 +453,8 @@ void CreateTabsAndWindows(
     IdToSessionTab* tabs,
     GroupIdToSessionTabGroup* tab_groups,
     IdToSessionWindow* windows,
-    SessionID* active_window_id) {
+    SessionID* active_window_id,
+    std::string* platform_session_id) {
   // If the file is corrupt (command with wrong size, or unknown command), we
   // still return true and attempt to restore what we we can.
   DVLOG(1) << "CreateTabsAndWindows";
@@ -905,6 +907,17 @@ void CreateTabsAndWindows(
         break;
       }
 
+      case kCommandSetPlatformSessionId: {
+        std::string id;
+        if (!RestoreSetPlatformSessionIdCommand(*command, &id)) {
+          DVLOG(1) << "Failed reading command " << command->id();
+          return;
+        }
+        DVLOG(1) << " restored platform_session_id=" << id;
+        *platform_session_id = id;
+        break;
+      }
+
       default:
         DVLOG(1) << "Failed reading an unknown command " << command->id();
         return;
@@ -1174,6 +1187,12 @@ std::unique_ptr<SessionCommand> CreateAddWindowExtraDataCommand(
                                    data);
 }
 
+std::unique_ptr<SessionCommand> CreateSetPlatformSessionIdCommand(
+    const std::string& platform_session_id) {
+  return CreateSetPlatformSessionIdCommand(kCommandSetPlatformSessionId,
+                                           platform_session_id);
+}
+
 bool ReplacePendingCommand(CommandStorageManager* command_storage_manager,
                            std::unique_ptr<SessionCommand>* command) {
   // We optimize page navigations, which can happen quite frequently and
@@ -1237,14 +1256,15 @@ bool IsClosingCommand(SessionCommand* command) {
 void RestoreSessionFromCommands(
     const std::vector<std::unique_ptr<SessionCommand>>& commands,
     std::vector<std::unique_ptr<SessionWindow>>* valid_windows,
-    SessionID* active_window_id) {
+    SessionID* active_window_id,
+    std::string* platform_session_id) {
   IdToSessionTab tabs;
   GroupIdToSessionTabGroup tab_groups;
   IdToSessionWindow windows;
 
   DVLOG(1) << "RestoreSessionFromCommands " << commands.size();
-  CreateTabsAndWindows(commands, &tabs, &tab_groups, &windows,
-                       active_window_id);
+  CreateTabsAndWindows(commands, &tabs, &tab_groups, &windows, active_window_id,
+                       platform_session_id);
   AddTabsToWindows(&tabs, &tab_groups, &windows);
   SortTabsBasedOnVisualOrderAndClear(&windows, valid_windows);
   UpdateSelectedTabIndex(valid_windows);

components/sessions/core/session_service_commands.h

@@ -111,6 +111,9 @@ SESSIONS_EXPORT std::unique_ptr<SessionCommand> CreateAddWindowExtraDataCommand(
     const std::string& key,
     const std::string& data);
 
+SESSIONS_EXPORT std::unique_ptr<SessionCommand>
+CreateSetPlatformSessionIdCommand(const std::string& platform_session_id);
+
 // Searches for a pending command using |command_storage_manager| that can be
 // replaced with |command|. If one is found, pending command is removed, the
 // command is added to the pending commands (taken ownership) and true is
@@ -129,7 +132,8 @@ SESSIONS_EXPORT bool IsClosingCommand(SessionCommand* command);
 SESSIONS_EXPORT void RestoreSessionFromCommands(
     const std::vector<std::unique_ptr<SessionCommand>>& commands,
     std::vector<std::unique_ptr<SessionWindow>>* valid_windows,
-    SessionID* active_window_id);
+    SessionID* active_window_id,
+    std::string* platform_session_id);
 
 }  // namespace sessions