Skip a first-run import on Mac when there is nothing left to import.

chrome/browser/first_run/first_run.cc

Index: chrome/browser/first_run/first_run.cc
diff --git a/chrome/browser/first_run/first_run.cc b/chrome/browser/first_run/first_run.cc
index b8409087ac10768f2df9019254482661e3622398..0de18c4ba121761cbc5ebb73ec62387419e12d7f 100644
--- a/chrome/browser/first_run/first_run.cc
+++ b/chrome/browser/first_run/first_run.cc
@@ -7,6 +7,7 @@
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/file_util.h"
+#include "base/lazy_instance.h"
 #include "base/metrics/histogram.h"
 #include "base/path_service.h"
 #include "base/stringprintf.h"
@@ -213,9 +214,14 @@ namespace internal {
 
 FirstRunState first_run_ = FIRST_RUN_UNKNOWN;
 
-installer::MasterPreferences* LoadMasterPrefs(FilePath* master_prefs_path)
-{
-  *master_prefs_path = FilePath(MasterPrefsPath());
+static base::LazyInstance<FilePath> master_prefs_path_for_testing
+    = LAZY_INSTANCE_INITIALIZER;
+
+installer::MasterPreferences* LoadMasterPrefs(FilePath* master_prefs_path) {
+  if (!master_prefs_path_for_testing.Get().empty())
+    *master_prefs_path = master_prefs_path_for_testing.Get();
+  else
+    *master_prefs_path = FilePath(MasterPrefsPath());
   if (master_prefs_path->empty())
     return NULL;
   installer::MasterPreferences* install_prefs =
@@ -547,6 +553,10 @@ void FirstRunBubbleLauncher::Observe(
   delete this;
 }
 
+void SetMasterPrefsPathForTesting(const FilePath& master_prefs) {
+  internal::master_prefs_path_for_testing.Get() = master_prefs;
+}
+
 ProcessMasterPreferencesResult ProcessMasterPreferences(
     const FilePath& user_data_dir,
     MasterPrefs* out_prefs) {