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..264ef8df6979eda1767cfe9e98da2d4c835cdeec 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 +76,19 @@ class SpellcheckCustomDictionary : public SpellcheckDictionary {
   void SetCustomWordListAndDelete(
       chrome::spellcheck_common::WordList* custom_words);
 
+  // Loads the dictionary file into |contents|. If the dictionary checksum is
+  // not valid, but backup checksum is valid, then restores the backup and loads
+  // that into |contents| instead.
+  void LoadDictionaryContentsReliably(std::string* contents);

[groby-ooo-7-16, 2012/12/04 00:16:30]

We should probably document somewhere that we expect our files to be UTF8, not
some fancy windows codepage or anything.

[please use gerrit instead, 2012/12/04 05:46:40]

Where is the best place to document this? Class comments? Method comments? Line
comments inside of LoadDictionaryContentsReliably?

+
+  // Backs up the original dictionary and checksum files, saves |contents| into
+  // the dictionary file, and saves the checksum of |contents| into the checksum
+  // file.

[groby-ooo-7-16, 2012/12/04 00:16:30]

I'd feel more comfortable having the checksum in the dictionary file, as the
first or last line. At least that way, you can still save dictionary files for
later use.

[please use gerrit instead, 2012/12/04 05:46:40]

Done.

+  void SaveDictionryContentsReliably(const std::string& contents);

[groby-ooo-7-16, 2012/12/04 00:16:30]

Spelling: Diction_a_ry (Hey, y u no spellcheck! ;)

[please use gerrit instead, 2012/12/04 05:46:40]

Done.

+
+  // Extract the |checksum| out of |contents|.
+  std::string GetChecksum(std::string* contents);

[groby-ooo-7-16, 2012/12/04 00:16:30]

const std::string& contents - it's not an out param.

[please use gerrit instead, 2012/12/04 05:46:40]

Added a comment to clarify: "If this method returns a non-empty checksum, then
|contents| have been truncated to exclude the checksum."

+
   // In-memory cache of the custom words file.
   chrome::spellcheck_common::WordList words_;
 
@@ -83,7 +97,10 @@ 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_;
 
   DISALLOW_COPY_AND_ASSIGN(SpellcheckCustomDictionary);
 };