Don't doom the wrong simple cache entry.

net/disk_cache/simple/simple_entry_impl.cc

Index: net/disk_cache/simple/simple_entry_impl.cc
diff --git a/net/disk_cache/simple/simple_entry_impl.cc b/net/disk_cache/simple/simple_entry_impl.cc
index e4e7220af7039c26924b58fb4737de40e995aaee..104674c0867bf7ef3f24f8d4f3f7ed6ecc1ff2bc 100644
--- a/net/disk_cache/simple/simple_entry_impl.cc
+++ b/net/disk_cache/simple/simple_entry_impl.cc
@@ -253,6 +253,8 @@ int SimpleEntryImpl::CreateEntry(Entry** out_entry,
 }
 
 int SimpleEntryImpl::DoomEntry(const CompletionCallback& callback) {
+  if (doomed_)
+    return net::OK;
   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_DOOM_CALL);
   net_log_.AddEvent(net::NetLog::TYPE_SIMPLE_CACHE_ENTRY_DOOM_BEGIN);
 
@@ -529,9 +531,9 @@ void SimpleEntryImpl::RemoveSelfFromBackend() {
 }
 
 void SimpleEntryImpl::MarkAsDoomed() {
+  doomed_ = true;
   if (!backend_.get())
     return;
-  doomed_ = true;
   backend_->index()->Remove(entry_hash_);
   RemoveSelfFromBackend();
 }