Debug the generic session restore failure.

chrome/browser/sessions/session_backend.cc

Index: chrome/browser/sessions/session_backend.cc
diff --git a/chrome/browser/sessions/session_backend.cc b/chrome/browser/sessions/session_backend.cc
index 39ec9b31f87007c0bdf2aec912f95dd3e6c1498c..bbb41035c67e4b701ece5c1bd2e20da9cd22f8aa 100644
--- a/chrome/browser/sessions/session_backend.cc
+++ b/chrome/browser/sessions/session_backend.cc
@@ -6,10 +6,18 @@
 
 #include <limits>
 
+#include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/memory/scoped_vector.h"
 #include "base/metrics/histogram.h"
+#include "base/string_number_conversions.h"
 #include "base/threading/thread_restrictions.h"
+#include "base/utf_string_conversions.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/prefs/scoped_user_pref_update.h"
+#include "chrome/common/pref_names.h"
+#include "content/public/browser/browser_thread.h"
 #include "net/base/file_stream.h"
 #include "net/base/net_errors.h"
 
@@ -267,9 +275,15 @@ void SessionBackend::DeleteLastSession() {
 void SessionBackend::MoveCurrentSessionToLastSession() {
   Init();
   current_session_file_.reset(NULL);
-
   const FilePath current_session_path = GetCurrentSessionPath();
   const FilePath last_session_path = GetLastSessionPath();
+  if (type_ == BaseSessionService::SESSION_RESTORE) {
+    // TODO(marja): This is only for debugging session restore failures; remove
+    // when debugging is done.
+    content::BrowserThread::PostTask(
+        content::BrowserThread::UI, FROM_HERE,
+        base::Bind(&SessionBackend::WriteDebugData, this));
+  }
   if (file_util::PathExists(last_session_path))
     file_util::Delete(last_session_path, false);
   if (file_util::PathExists(current_session_path)) {
@@ -405,3 +419,28 @@ FilePath SessionBackend::GetCurrentSessionPath() {
     path = path.AppendASCII(kCurrentSessionFileName);
   return path;
 }
+
+void SessionBackend::WriteDebugData() {
+  PrefService* prefs = g_browser_process->local_state();
+  if (!prefs)
+    return;
+  ListPrefUpdate update(prefs, prefs::kSessionRestoreFilesCycled);
+  ListValue* list = update.Get();
+  while (list->GetSize() > 10)
+    list->Remove(0, NULL);
+  char time_string[32];
+  time_t now = base::Time::Now().ToTimeT();
+  strftime(time_string, 32, "%d.%m.%Y %H:%M:%S", localtime(&now));
+  list->Append(new StringValue(
+#if defined(OS_POSIX)
+      base::IntToString(getpid()) + " " +
+#endif
+      std::string(time_string) + " " +
+#if defined(OS_WIN)
+      WideToUTF8(path_to_dir_.BaseName().value()) + " " +
+      WideToUTF8(CommandLine::ForCurrentProcess()->GetCommandLineString())));
+#else
+      path_to_dir_.BaseName().value() + " " +
+      CommandLine::ForCurrentProcess()->GetCommandLineString()));
+#endif
+}