Cache Backend Proxy to intercept all cache events from the IO thread.

net/disk_cache/simple/simple_disk_format.cc

Index: net/disk_cache/simple/simple_disk_format.cc
diff --git a/net/disk_cache/simple/simple_disk_format.cc b/net/disk_cache/simple/simple_disk_format.cc
index 9e6beea193686c14c6ae7ef611b3a9d149621117..1b7a159a7fd793abd2735734ad5566a95352ce7e 100644
--- a/net/disk_cache/simple/simple_disk_format.cc
+++ b/net/disk_cache/simple/simple_disk_format.cc
@@ -12,6 +12,11 @@
 
 namespace disk_cache {
 
+SimpleFileHeader::SimpleFileHeader() {
+  // Make hashing repeatable: leave no padding bytes untouched.
+  memset(this, 0, sizeof(*this));
+}
+
 std::string GetEntryHashForKey(const std::string& key) {
   const std::string sha_hash = base::SHA1HashString(key);
   const std::string key_hash = base::StringPrintf(