Disk cache: Add a hash to the entry's internal data.

net/disk_cache/storage_block-inl.h

Index: net/disk_cache/storage_block-inl.h
===================================================================
--- net/disk_cache/storage_block-inl.h	(revision 110637)
+++ net/disk_cache/storage_block-inl.h	(working copy)
@@ -9,6 +9,7 @@
 #include "net/disk_cache/storage_block.h"
 
 #include "base/logging.h"
+#include "net/disk_cache/hash.h"
 #include "net/disk_cache/trace.h"
 
 namespace disk_cache {
@@ -98,6 +99,11 @@
   return (NULL != data_);
 }
 
+template<typename T> bool StorageBlock<T>::VerifyHash() const {
+  uint32 hash = CalculateHash();
+  return (!data_->self_hash || data_->self_hash == hash);
+}
+
 template<typename T> bool StorageBlock<T>::own_data() const {
   return own_data_;
 }
@@ -123,6 +129,7 @@
 
 template<typename T> bool StorageBlock<T>::Store() {
   if (file_ && data_) {
+    data_->self_hash = CalculateHash();
     if (file_->Store(this)) {
       modified_ = false;
       return true;
@@ -156,6 +163,10 @@
   }
 }
 
+template<typename T> uint32 StorageBlock<T>::CalculateHash() const {
+  return Hash(reinterpret_cast<char*>(data_), offsetof(T, self_hash));
+}
+
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_STORAGE_BLOCK_INL_H_