Improve reliability of custom spelling dictionary file.

chrome/browser/spellchecker/spellcheck_custom_dictionary.h

Index: chrome/browser/spellchecker/spellcheck_custom_dictionary.h
diff --git a/chrome/browser/spellchecker/spellcheck_custom_dictionary.h b/chrome/browser/spellchecker/spellcheck_custom_dictionary.h
index b1d6045f1db0231c841c7e57c7738cf5b490a0c7..078b6c6a91e2ad4b59f0840d88a580859cc9ffc6 100644
--- a/chrome/browser/spellchecker/spellcheck_custom_dictionary.h
+++ b/chrome/browser/spellchecker/spellcheck_custom_dictionary.h
@@ -11,6 +11,7 @@
 #include "base/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "chrome/browser/spellchecker/spellcheck_dictionary.h"
 #include "chrome/common/spellcheck_common.h"
 
@@ -75,6 +76,22 @@ class SpellcheckCustomDictionary : public SpellcheckDictionary {
   void SetCustomWordListAndDelete(
       chrome::spellcheck_common::WordList* custom_words);
 
+  // Loads the dictionary file into |custom_words|. If the dictionary checksum
+  // is not valid, but backup checksum is valid, then restores the backup and
+  // loads that into |custom_words| instead.

[groby-ooo-7-16, 2012/12/05 00:56:19]

"If the backup is invalid too, |custom_words| will be cleared"

[please use gerrit instead, 2012/12/05 16:51:26]

Done.

+  void LoadDictionaryFileReliably(
+      chrome::spellcheck_common::WordList* custom_words);
+
+  // Backs up the original dictionary and checksum files, saves |custom_words|

[groby-ooo-7-16, 2012/12/05 00:56:19]

- "and checksum files"

[please use gerrit instead, 2012/12/05 16:51:26]

Done.

+  // and its checksum into the dictionary file.
+  void SaveDictionaryFileReliably(
+      const chrome::spellcheck_common::WordList& custom_words);
+
+  // Extracts the checksum out of |contents| and truncates |contents| to exclude
+  // the checksum line. Returns an empty string if |contents| do not contain a
+  // checksum.
+  std::string GetChecksum(std::string* contents);
+
   // In-memory cache of the custom words file.
   chrome::spellcheck_common::WordList words_;
 
@@ -83,7 +100,10 @@ class SpellcheckCustomDictionary : public SpellcheckDictionary {
 
   base::WeakPtrFactory<SpellcheckCustomDictionary> weak_ptr_factory_;
 
-  std::vector<Observer*> observers_;
+  ObserverList<Observer> observers_;
+
+  const FilePath::StringType backup_extension_;
+  const std::string checksum_prefix_;

[groby-ooo-7-16, 2012/12/05 00:56:19]

Why a member? It never changes its value, and it's only used in one function?

I'd suggest a constant in anon namespace and creating the string on the fly in
GetChecksum

(Ditto for backup_extension_)

[please use gerrit instead, 2012/12/05 16:51:26]

Done.

 
   DISALLOW_COPY_AND_ASSIGN(SpellcheckCustomDictionary);
 };