RFC: use some in-memory state in SimpleCache to quickly cache-miss some CantConditionalize cases

net/disk_cache/simple/simple_index.h

Index: net/disk_cache/simple/simple_index.h
diff --git a/net/disk_cache/simple/simple_index.h b/net/disk_cache/simple/simple_index.h
index 6740c2c91e2b810caa5d2092d93baff6b616c85e..9131bc37e098742732c1ec1b9027f18523fbba2c 100644
--- a/net/disk_cache/simple/simple_index.h
+++ b/net/disk_cache/simple/simple_index.h
@@ -58,9 +58,12 @@ class NET_EXPORT_PRIVATE EntryMetadata {
   uint32_t GetEntrySize() const;
   void SetEntrySize(base::StrictNumeric<uint32_t> entry_size);
 
+  uint8_t GetMemoryEntryData() const { return memory_entry_data_; }
+  void SetMemoryEntryData(uint8_t val) { memory_entry_data_ = val; }
+
   // Serialize the data into the provided pickle.
   void Serialize(base::Pickle* pickle) const;
-  bool Deserialize(base::PickleIterator* it);
+  bool Deserialize(base::PickleIterator* it, bool has_memory_entry_data);
 
   static base::TimeDelta GetLowerEpsilonForTimeComparisons() {
     return base::TimeDelta::FromSeconds(1);
@@ -79,7 +82,9 @@ class NET_EXPORT_PRIVATE EntryMetadata {
   // are originally calculated as >32-bit types, the actual necessary size for
   // each shouldn't exceed 32 bits, so we use 32-bit types here.
   uint32_t last_used_time_seconds_since_epoch_;
-  uint32_t entry_size_;  // Storage size in bytes.
+  // Storage size in 256-byte blocks
+  uint32_t entry_size_ : 24;
+  uint32_t memory_entry_data_ : 8;
 };
 static_assert(sizeof(EntryMetadata) == 8, "incorrect metadata size");
 
@@ -127,6 +132,9 @@ class NET_EXPORT_PRIVATE SimpleIndex
   // iff the entry exist in the index.
   bool UseIfExists(uint64_t entry_hash);
 
+  uint8_t GetMemoryEntryData(uint64_t entry_hash) const;
+  void SetMemoryEntryData(uint64_t entry_hash, uint8_t value);
+
   void WriteToDisk(IndexWriteToDiskReason reason);
 
   // Update the size (in bytes) of an entry, in the metadata stored in the