Extend scoped_ptr to be closer to unique_ptr. Support custom deleters, and deleting arrays.

This is based on the modifications by "Geoffrey Romer"
 <gromer@google.com> to Google's internal version of scoped_ptr<>.  All cleaver tricks are his, not mine. :)

It brings most of the features of C++11's unique_ptr<> into this class and should eliminate the need for scoped_array<>, scoped_malloc_free<>, and possibly a few other scopers.  Please refer to the unique_ptr<> API for documentation.

Divergence from unique_ptr<>:
1) DefaultDeleter<T[n]> (sized-arrays) is explicitly disabled because this construct would cause the single-object delete to be called on a pointer to a T[n]. It is impossible to construct a single-object new expression that returns a T[n]*. You can only get this with new[] which should correspond to DefaultDeleter<T[n][]>. This issue has been raised with the C++ LWG as it is possible a unique_ptr<> spec defect.

2) Reference types for Deleters are not supported. This simplifies implementation significantly because there is no need to distinguish between the converting constructor + converting assignment operator and their move constructor + move assignment operator.

4) Move-only Deleters are not supported. Avoids the need to emulate std::forward().

BUG=109874
TBR=dhollowa,kinuko,ananta,hans,scherkus

Review URL: https://codereview.chromium.org/11149006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@174057 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 5 insertions, 4 deletions

diff --git a/media/base/audio_bus.h b/media/base/audio_bus.h
index 5ea4e08..d94ab38 100644
--- a/media/base/audio_bus.h
+++ b/media/base/audio_bus.h
@@ -93,7 +93,7 @@ class MEDIA_EXPORT AudioBus {
   void ZeroFramesPartial(int start_frame, int frames);
 
  private:
-  friend class scoped_ptr<AudioBus>;
+  friend struct base::DefaultDeleter<AudioBus>;
   ~AudioBus();
 
   AudioBus(int channels, int frames);
diff --git a/media/base/message_loop_factory.h b/media/base/message_loop_factory.h
index f399b48..0989174 100644
--- a/media/base/message_loop_factory.h
+++ b/media/base/message_loop_factory.h
@@ -38,8 +38,9 @@ class MEDIA_EXPORT MessageLoopFactory {
   scoped_refptr<base::MessageLoopProxy> GetMessageLoop(Type type);
 
  private:
-  // Only allow scoped_ptr<> to delete factory.
-  friend class scoped_ptr<MessageLoopFactory>;
+  // Restrict who can delete the factory to scoped_ptr<>. scoped_ptr<> uses
+  // base::DefaultDeleter.
+  friend struct base::DefaultDeleter<MessageLoopFactory>;
   ~MessageLoopFactory();
 
   // Returns the thread associated with |type| creating a new thread if needed.
diff --git a/media/base/serial_runner.h b/media/base/serial_runner.h
index 16fa6f3..a59c775 100644
--- a/media/base/serial_runner.h
+++ b/media/base/serial_runner.h
@@ -56,7 +56,7 @@ class SerialRunner {
       const Queue& bound_fns, const PipelineStatusCB& done_cb);
 
  private:
-  friend class scoped_ptr<SerialRunner>;
+  friend struct base::DefaultDeleter<SerialRunner>;
 
   SerialRunner(const Queue& bound_fns, const PipelineStatusCB& done_cb);
   ~SerialRunner();