Add autofill metrics to dig into the failure case.

chrome/browser/autofill/form_structure.h

Index: chrome/browser/autofill/form_structure.h
diff --git a/chrome/browser/autofill/form_structure.h b/chrome/browser/autofill/form_structure.h
index ad0c411fe6da7a8e0cb5cbf67619706cfe7c5386..1c5e7afacd482ad9c45e917d6b1dc7c0023d8384 100644
--- a/chrome/browser/autofill/form_structure.h
+++ b/chrome/browser/autofill/form_structure.h
@@ -38,7 +38,7 @@ class AutoFillMetrics;
 class FormStructure {
  public:
   explicit FormStructure(const webkit_glue::FormData& form);
-  ~FormStructure();
+  virtual ~FormStructure();
 
   // Encodes the XML upload request from this FormStructure.
   bool EncodeUploadRequest(bool auto_fill_used,
@@ -106,6 +106,10 @@ class FormStructure {
   bool operator==(const webkit_glue::FormData& form) const;
   bool operator!=(const webkit_glue::FormData& form) const;
 
+ protected:
+  // For tests.
+  ScopedVector<AutoFillField>* fields() { return &fields_; }
+
  private:
   enum EncodeRequestType {
     QUERY,