[SessionService] Adding debug information & fixing app reparenting.

This fixes the app reparenting issue introduced by this CL:
https://chromium-review.googlesource.com/c/chromium/src/+/5899682

That CL deleted some session restore stuff that seemed unnecessary.
Unfortunately there are no tests in this area. So this CL adds that
logic back due to the below bug being found.

This CL also adds a lot more helpful information to
chrome://internals/session-service.

Bug: 373461941
Change-Id: I701e0588c02a2ef5beb59516ad5ffc79dc93f585
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5938537
Auto-Submit: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1369633}

components/sessions/core/command_storage_manager.cc

@@ -4,6 +4,7 @@
 
 #include "components/sessions/core/command_storage_manager.h"
 
+#include <memory>
 #include <utility>
 
 #include "base/functional/bind.h"
@@ -14,8 +15,10 @@
 #include "base/task/single_thread_task_runner.h"
 #include "base/task/thread_pool.h"
 #include "base/threading/thread.h"
+#include "base/values.h"
 #include "components/sessions/core/command_storage_backend.h"
 #include "components/sessions/core/command_storage_manager_delegate.h"
+#include "components/sessions/core/session_command.h"
 #include "crypto/random.h"
 
 namespace sessions {
@@ -31,6 +34,14 @@ void AdaptGetLastSessionCommands(
   std::move(callback).Run(std::move(result.commands), result.error_reading);
 }
 
+#if DCHECK_IS_ON()
+base::Value CommandToDebugValue(const SessionCommand& command) {
+  // There is no convenience function to transform the pickled contents into the
+  // payload struct itself, so just output the id for now.
+  return base::Value(command.id());
+}
+#endif  // DCHECK_IS_ON()
+
 }  // namespace
 
 CommandStorageManager::CommandStorageManager(
@@ -133,6 +144,16 @@ void CommandStorageManager::Save() {
   if (pending_commands_.empty())
     return;
 
+#if DCHECK_IS_ON()
+  for (const std::unique_ptr<SessionCommand>& command : pending_commands_) {
+    written_commands_reverse_debug_log_.push_front(
+        CommandToDebugValue(*command));
+  }
+  if (written_commands_reverse_debug_log_.size() > kMaxLogSize) {
+    written_commands_reverse_debug_log_.resize(kMaxLogSize);
+  }
+#endif  // DCHECK_IS_ON()
+
   std::vector<uint8_t> crypto_key;
   if (use_crypto_ && pending_reset_) {
     crypto_key = CreateCryptoKey();
@@ -178,6 +199,24 @@ void CommandStorageManager::GetLastSessionCommands(
       base::BindOnce(&AdaptGetLastSessionCommands, std::move(callback)));
 }
 
+#if DCHECK_IS_ON()
+base::Value CommandStorageManager::ToDebugValue() const {
+  base::Value::Dict debug_value;
+  debug_value.Set("use_crypto", use_crypto_);
+  for (const std::unique_ptr<SessionCommand>& command : pending_commands_) {
+    debug_value.EnsureList("pending_commands")
+        ->Append(CommandToDebugValue(*command));
+  }
+  debug_value.Set("pending_reset", pending_reset_);
+  debug_value.Set("commands_since_reset", commands_since_reset_);
+  for (const base::Value& log_item : written_commands_reverse_debug_log_) {
+    debug_value.EnsureList("written_commands_reverse_debug_log")
+        ->Append(log_item.Clone());
+  }
+  return base::Value(std::move(debug_value));
+}
+#endif  // DCHECK_IS_ON()
+
 void CommandStorageManager::OnErrorWritingToFile() {
   delegate_->OnErrorWritingSessionCommands();
 }

components/sessions/core/command_storage_manager.h

@@ -7,6 +7,7 @@
 
 #include <stddef.h>
 
+#include <list>
 #include <memory>
 #include <vector>
 
@@ -18,6 +19,10 @@
 #include "base/task/sequenced_task_runner.h"
 #include "components/sessions/core/sessions_export.h"
 
+namespace base {
+class Value;
+}
+
 namespace sessions {
 class CommandStorageManagerDelegate;
 class SessionCommand;
@@ -130,6 +135,14 @@ class SESSIONS_EXPORT CommandStorageManager {
   // deleted.
   void GetLastSessionCommands(GetCommandsCallback callback);
 
+#if DCHECK_IS_ON()
+  // Returns the state of this class and logs for the
+  // chrome://internals/session-service debug page. The logs are in reverse
+  // order for truncation ease. This value is NOT STABLE - do not rely on it's
+  // contents for anything.
+  base::Value ToDebugValue() const;
+#endif  // DCHECK_IS_ON()
+
  private:
   friend class CommandStorageManagerTestHelper;
 
@@ -160,6 +173,12 @@ class SESSIONS_EXPORT CommandStorageManager {
   // all tasks *must* be processed in the order they are scheduled.
   scoped_refptr<base::SequencedTaskRunner> backend_task_runner_;
 
+#if DCHECK_IS_ON()
+  // Used to store debug log entries for this command manager.
+  constexpr static int kMaxLogSize = 100;
+  std::list<base::Value> written_commands_reverse_debug_log_;
+#endif  // DCHECK_IS_ON()
+
   base::WeakPtrFactory<CommandStorageManager> weak_factory_{this};
 
   // Used solely for saving after a delay, and not to be used for any other