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..cedbb734c2c762df57ad3b030f80f276ea0b8278 100644
--- a/chrome/browser/spellchecker/spellcheck_custom_dictionary.h
+++ b/chrome/browser/spellchecker/spellcheck_custom_dictionary.h
@@ -11,10 +11,19 @@
 #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"
 
-// Defines a custom dictionary which users can add their own words to.
+// Defines a custom dictionary where users can add their own words. All words
+// must be UTF8, between 1 and 128 bytes long, and without ASCII whitespace.
+// The dictionary contains its own checksum when saved on disk. Example
+// dictionary file contents:
+//
+//   bar
+//   foo
+//   checksum_v1 = ec3df4034567e59e119fcf87f2d9bad4
+//
 class SpellcheckCustomDictionary : public SpellcheckDictionary {
  public:
   class Observer {
@@ -33,8 +42,8 @@ class SpellcheckCustomDictionary : public SpellcheckDictionary {
   const chrome::spellcheck_common::WordList& GetWords() const;
 
   // Populates the |custom_words| with the list of words in the custom
-  // dictionary file. Makes sure that the custom dictionary file is sorted and
-  // does not have duplicates.
+  // dictionary file. Makes sure that the custom dictionary file is sorted, does
+  // not have duplicates, and contains only valid words.
   void LoadDictionaryIntoCustomWordList(
       chrome::spellcheck_common::WordList* custom_words);
 
@@ -42,8 +51,8 @@ class SpellcheckCustomDictionary : public SpellcheckDictionary {
   // member variable. Does not delete the memory at |custom_words|.
   void SetCustomWordList(chrome::spellcheck_common::WordList* custom_words);
 
-  // Adds the given word to the custom words list and inform renderer of the
-  // update. Returns false for duplicate words.
+  // Adds the given word to the custom words list and informs renderers of the
+  // update. Returns false for duplicate and invalid words.
   bool AddWord(const std::string& word);
 
   // Returns false for duplicate words.
@@ -51,8 +60,9 @@ class SpellcheckCustomDictionary : public SpellcheckDictionary {
 
   void WriteWordToCustomDictionary(const std::string& word);
 
-  // Removes the given word from the custom words list and informs renderer of
-  // the update. Returns false for words that are not in the dictionary.
+  // Removes the given word from the custom words list and informs renderers of
+  // the update. Returns false for words that are not in the dictionary and
+  // invalid words.
   bool RemoveWord(const std::string& word);
 
   // Returns false for words that are not in the dictionary.
@@ -75,6 +85,18 @@ 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. If the backup is invalid too, then
+  // clears |custom_words|.
+  void LoadDictionaryFileReliably(
+      chrome::spellcheck_common::WordList* custom_words);
+
+  // Backs up the original dictionary, saves |custom_words| and its checksum
+  // into the dictionary file.
+  void SaveDictionaryFileReliably(
+      const chrome::spellcheck_common::WordList& custom_words);
+
   // In-memory cache of the custom words file.
   chrome::spellcheck_common::WordList words_;
 
@@ -83,7 +105,7 @@ class SpellcheckCustomDictionary : public SpellcheckDictionary {
 
   base::WeakPtrFactory<SpellcheckCustomDictionary> weak_ptr_factory_;
 
-  std::vector<Observer*> observers_;
+  ObserverList<Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(SpellcheckCustomDictionary);
 };