Introduce the plumbing necessary to report Unrecoverable error from model safe workers.

chrome/browser/sync/syncable/syncable.h

Index: chrome/browser/sync/syncable/syncable.h
diff --git a/chrome/browser/sync/syncable/syncable.h b/chrome/browser/sync/syncable/syncable.h
index 4f8875f92ddac46987a8a898a70f446fbde1fc8c..25b23590401c60cbdc4ec85e1d2f3ec857027bb3 100644
--- a/chrome/browser/sync/syncable/syncable.h
+++ b/chrome/browser/sync/syncable/syncable.h
@@ -53,7 +53,6 @@ namespace syncable {
 class DirectoryChangeDelegate;
 class TransactionObserver;
 class Entry;
-
 std::ostream& operator<<(std::ostream& s, const Entry& e);
 
 class DirectoryBackingStore;
@@ -874,6 +873,9 @@ class Directory {
   void AddTransactionObserver(TransactionObserver* observer);
   void RemoveTransactionObserver(TransactionObserver* observer);
 
+  void set_unrecoverable_error();
+  bool unrecoverable_error() const;
+
  protected:  // for friends, mainly used by Entry constructors
   virtual EntryKernel* GetEntryByHandle(int64 handle);
   virtual EntryKernel* GetEntryByHandle(int64 metahandle,
@@ -1152,6 +1154,11 @@ class Directory {
   Kernel* kernel_;
 
   DirectoryBackingStore* store_;
+
+  // Keep a copy to check before performing some shutdown operations.
+  // Otherwise if the store is corrupted and we perform those operations
+  // anyway(as part of sync shutdown) then we will crash there.
+  bool unrecoverable_error_;
 };
 
 class ScopedKernelLock {
@@ -1171,6 +1178,8 @@ class BaseTransaction {
   inline Directory* directory() const { return directory_; }
   inline Id root_id() const { return Id(); }
 
+  void set_unrecoverable_error();
+
   virtual ~BaseTransaction();
 
  protected: