Remove void** from disk_cache interface.

net/disk_cache/disk_cache.h

Index: net/disk_cache/disk_cache.h
diff --git a/net/disk_cache/disk_cache.h b/net/disk_cache/disk_cache.h
index 4f64b9afb02ac4219532491f592d0c7b269985fb..da73433eeff3b210aa6f36496ec6c43adb8a2e31 100644
--- a/net/disk_cache/disk_cache.h
+++ b/net/disk_cache/disk_cache.h
@@ -13,6 +13,7 @@
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "net/base/cache_type.h"
 #include "net/base/completion_callback.h"
@@ -62,6 +63,11 @@ NET_EXPORT int CreateCacheBackend(
 // The root interface for a disk cache instance.
 class NET_EXPORT Backend {
  public:
+  class EnumerationState {
+   public:
+    virtual ~EnumerationState() = 0;
+  };
+  typedef scoped_ptr<EnumerationState> Iterator;
   typedef net::CompletionCallback CompletionCallback;
 
   // If the backend is destroyed when there are operations in progress (any
@@ -70,7 +76,7 @@ class NET_EXPORT Backend {
   // half way (for instance, dooming just a few entries). Note that pending IO
   // for a given Entry (as opposed to the Backend) will still generate a
   // callback from within this method.
-  virtual ~Backend() {}
+  virtual ~Backend();

[gavinp, 2014/09/04 17:52:52]

As long as we were adding disk_cache.cc (for the body of
EnumerationState::~EnumerationState()), it seemed lke a good idea to move this
there as well, in keeping with
http://www.chromium.org/developers/coding-style/cpp-dos-and-donts#TOC-Stop-in...
.

It saves the linker a bit of churn, anyway.

 
   // Returns the type of this cache.
   virtual net::CacheType GetCacheType() const = 0;
@@ -123,32 +129,15 @@ class NET_EXPORT Backend {
   virtual int DoomEntriesSince(base::Time initial_time,
                                const CompletionCallback& callback) = 0;
 
-  // Enumerates the cache. Initialize |iter| to NULL before calling this method
-  // the first time. That will cause the enumeration to start at the head of
-  // the cache. For subsequent calls, pass the same |iter| pointer again without
-  // changing its value. This method returns ERR_FAILED when there are no more
-  // entries to enumerate. When the entry pointer is no longer needed, its
-  // Close method should be called. The return value is a net error code. If
-  // this method returns ERR_IO_PENDING, the |callback| will be invoked when the
-  // |next_entry| is available. The pointer to receive the |next_entry| must
-  // remain valid until the operation completes.
-  //
-  // NOTE: This method does not modify the last_used field of the entry, and
-  // therefore it does not impact the eviction ranking of the entry. However,
-  // an enumeration will go through all entries on the cache only if the cache
-  // is not modified while the enumeration is taking place. Significantly
-  // altering the entry pointed by |iter| (for example, deleting the entry) will
-  // invalidate |iter|. Performing operations on an entry that modify the entry
-  // may result in loops in the iteration, skipped entries or similar.
-  virtual int OpenNextEntry(void** iter, Entry** next_entry,
+  // Enumerates the cache. Initialize |iter| to NULL for the first call, and
+  // provide it again for subsequent calls. For each successful step of
+  // enumeration, OpenNextEntry returns OK and provides |next_entry|, which is
+  // open and should be closed by the caller. This method returns ERR_FAILED at
+  // the end of enumeration. If any entry in a cache is modified during
+  // iteration, then the result of this function is thereafter undefined.
+  virtual int OpenNextEntry(Iterator* iter, Entry** next_entry,
                             const CompletionCallback& callback) = 0;
 
-  // Releases iter without returning the next entry. Whenever OpenNextEntry()
-  // returns true, but the caller is not interested in continuing the
-  // enumeration by calling OpenNextEntry() again, the enumeration must be
-  // ended by calling this method with iter returned by OpenNextEntry().
-  virtual void EndEnumeration(void** iter) = 0;
-
   // Return a list of cache statistics.
   virtual void GetStats(
       std::vector<std::pair<std::string, std::string> >* stats) = 0;
@@ -310,7 +299,7 @@ class NET_EXPORT Entry {
   virtual int ReadyForSparseIO(const CompletionCallback& callback) = 0;
 
  protected:
-  virtual ~Entry() {}
+  virtual ~Entry();

[gavinp, 2014/09/04 17:52:52]

(see discussion at
https://codereview.chromium.org/542733002/diff/120001/net/disk_cache/disk_cac...
for an explanation of this)

 };
 
 struct EntryDeleter {