Create a new disk_cache type, SHADER_CACHE.

net/disk_cache/backend_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/disk_cache/backend_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
@@ skipping 460 matching lines @@
   bool previous_crash = (data_->header.crash != 0);
   data_->header.crash = 1;
 
   if (!block_files_.Init(create_files))
     return net::ERR_FAILED;
 
   // We want to minimize the changes to cache for an AppCache.
   if (cache_type() == net::APP_CACHE) {
     DCHECK(!new_eviction_);
     read_only_ = true;
+  } else if (cache_type() == net::SHADER_CACHE) {
+    DCHECK(!new_eviction_);
   }
 
   eviction_.Init(this);
 
   // stats_ and rankings_ may end up calling back to us so we better be enabled.
   disabled_ = false;
   if (!stats_.Init(this, &data_->header.stats))
     return net::ERR_FAILED;
 
   disabled_ = !rankings_.Init(this, new_eviction_);
@@ skipping 172 matching lines @@
 
 void BackendImpl::SyncOnExternalCacheHit(const std::string& key) {
   if (disabled_)
     return;
 
   uint32 hash = base::Hash(key);
   bool error;
   EntryImpl* cache_entry = MatchEntry(key, hash, false, Addr(), &error);
   if (cache_entry) {
     if (ENTRY_NORMAL == cache_entry->entry()->Data()->state) {
-      UpdateRank(cache_entry, false);
+      UpdateRank(cache_entry, cache_type() == net::SHADER_CACHE);
     }
     cache_entry->Release();
   }
 }
 
 EntryImpl* BackendImpl::OpenEntryImpl(const std::string& key) {
   if (disabled_)
     return NULL;
 
   TimeTicks start = TimeTicks::Now();
@@ skipping 231 matching lines @@
 
 void BackendImpl::DeleteBlock(Addr block_address, bool deep) {
   block_files_.DeleteBlock(block_address, deep);
 }
 
 LruData* BackendImpl::GetLruData() {
   return &data_->header.lru;
 }
 
 void BackendImpl::UpdateRank(EntryImpl* entry, bool modified) {
-  if (!read_only_) {
-    eviction_.UpdateRank(entry, modified);
-  }
+  if (read_only_ || (!modified && cache_type() == net::SHADER_CACHE))
+    return;
+  eviction_.UpdateRank(entry, modified);
 }
 
 void BackendImpl::RecoveredEntry(CacheRankingsBlock* rankings) {
   Addr address(rankings->Data()->contents);
   EntryImpl* cache_entry = NULL;
   if (NewEntry(address, &cache_entry)) {
     STRESS_NOTREACHED();
     return;
   }
 
@@ skipping 1301 matching lines @@
     if (total_memory > kMaxBuffersSize || total_memory <= 0)
       total_memory = kMaxBuffersSize;
 
     done = true;
   }
 
   return static_cast<int>(total_memory);
 }
 
 }  // namespace disk_cache