Downgrade all CHECKs to DCHECKs in SimpleCache backend.

After we're sure we have fixed 317138, let's drop these CHECKs. Also,
celebrate!

R=ttuttle@chromium.org
BUG=317138

Review URL: https://codereview.chromium.org/509993002

Cr-Commit-Position: refs/heads/master@{#296972}

net/disk_cache/simple/simple_backend_impl.cc

@@ -280,15 +280,13 @@ int SimpleBackendImpl::GetMaxFileSize() const {
 }
 
 void SimpleBackendImpl::OnDoomStart(uint64 entry_hash) {
-  // TODO(ttuttle): Revert to DCHECK once http://crbug.com/317138 is fixed.
-  CHECK_EQ(0u, entries_pending_doom_.count(entry_hash));
+  DCHECK_EQ(0u, entries_pending_doom_.count(entry_hash));
   entries_pending_doom_.insert(
       std::make_pair(entry_hash, std::vector<Closure>()));
 }
 
 void SimpleBackendImpl::OnDoomComplete(uint64 entry_hash) {
-  // TODO(ttuttle): Revert to DCHECK once http://crbug.com/317138 is fixed.
-  CHECK_EQ(1u, entries_pending_doom_.count(entry_hash));
+  DCHECK_EQ(1u, entries_pending_doom_.count(entry_hash));
   base::hash_map<uint64, std::vector<Closure> >::iterator it =
       entries_pending_doom_.find(entry_hash);
   std::vector<Closure> to_run_closures;
@@ -314,11 +312,8 @@ void SimpleBackendImpl::DoomEntries(std::vector<uint64>* entry_hashes,
   //    SimpleSynchronousEntry::DoomEntrySet and delete the files en masse.
   for (int i = mass_doom_entry_hashes->size() - 1; i >= 0; --i) {
     const uint64 entry_hash = (*mass_doom_entry_hashes)[i];
-    // TODO(ttuttle): Revert to DCHECK once http://crbug.com/317138 is fixed.
-    CHECK(active_entries_.count(entry_hash) == 0 ||
-          entries_pending_doom_.count(entry_hash) == 0)
-        << "The entry 0x" << std::hex << entry_hash
-        << " is both active and pending doom.";
+    DCHECK(active_entries_.count(entry_hash) == 0 ||
+           entries_pending_doom_.count(entry_hash) == 0);
     if (!active_entries_.count(entry_hash) &&
         !entries_pending_doom_.count(entry_hash)) {
       continue;
@@ -337,8 +332,7 @@ void SimpleBackendImpl::DoomEntries(std::vector<uint64>* entry_hashes,
            it = to_doom_individually_hashes.begin(),
            end = to_doom_individually_hashes.end(); it != end; ++it) {
     const int doom_result = DoomEntryFromHash(*it, barrier_callback);
-    // TODO(ttuttle): Revert to DCHECK once http://crbug.com/317138 is fixed.
-    CHECK_EQ(net::ERR_IO_PENDING, doom_result);
+    DCHECK_EQ(net::ERR_IO_PENDING, doom_result);
     index_->Remove(*it);
   }