Collect statistics on importing empty usernames and passwords from other browsers.

chrome/browser/importer/in_process_importer_bridge.cc

Index: chrome/browser/importer/in_process_importer_bridge.cc
diff --git a/chrome/browser/importer/in_process_importer_bridge.cc b/chrome/browser/importer/in_process_importer_bridge.cc
index c5c5927af84fdb7fc309236144633a70690a5ff6..853788ea8c1c3070adcd4aa19b91ba8f82917868 100644
--- a/chrome/browser/importer/in_process_importer_bridge.cc
+++ b/chrome/browser/importer/in_process_importer_bridge.cc
@@ -5,6 +5,7 @@
 #include "chrome/browser/importer/in_process_importer_bridge.h"
 
 #include "base/bind.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/files/file_util.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ -62,6 +63,15 @@ history::VisitSource ConvertImporterVisitSourceToHistoryVisitSource(
   return history::SOURCE_SYNCED;
 }
 
+// http://crbug.com/404012. Let's see where the empty fields come from.
+void CheckForEmptyUsernameAndPassword(const autofill::PasswordForm& form) {
+  if (form.username_value.empty() &&
+      form.password_value.empty() &&
+      !form.blacklisted_by_user) {
+    base::debug::DumpWithoutCrashing();
+  }
+}
+
 }  // namespace
 
 using content::BrowserThread;
@@ -251,6 +261,7 @@ void InProcessImporterBridge::SetFirefoxSearchEnginesXMLData(
 
 void InProcessImporterBridge::SetPasswordForm(
     const autofill::PasswordForm& form) {
+  CheckForEmptyUsernameAndPassword(form);
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&ProfileWriter::AddPasswordForm, writer_, form));