Add MakeUnique from chromium and change StunMessage::AddAttribute to take a unique_ptr.

webrtc/p2p/base/stun.h

Index: webrtc/p2p/base/stun.h
diff --git a/webrtc/p2p/base/stun.h b/webrtc/p2p/base/stun.h
index 532fe5bec9e947f127972bc2f4f27c0b4ca3563d..ab200687f5ba4d8855730ade4dde2786c0354124 100644
--- a/webrtc/p2p/base/stun.h
+++ b/webrtc/p2p/base/stun.h
@@ -159,8 +159,7 @@ class StunMessage {
   const StunUInt16ListAttribute* GetUnknownAttributes() const;
 
   // Takes ownership of the specified attribute and adds it to the message.
-  // TODO(zstein): Take a unique_ptr instead of a raw pointer.
-  void AddAttribute(StunAttribute* attr);
+  void AddAttribute(std::unique_ptr<StunAttribute> attr);
 
   // Validates that a raw STUN message has a correct MESSAGE-INTEGRITY value.
   // This can't currently be done on a StunMessage, since it is affected by
@@ -233,13 +232,15 @@ class StunAttribute {
                                StunMessage* owner);
   // TODO: Allow these create functions to take parameters, to reduce
   // the amount of work callers need to do to initialize attributes.
-  static StunAddressAttribute* CreateAddress(uint16_t type);
-  static StunXorAddressAttribute* CreateXorAddress(uint16_t type);
-  static StunUInt32Attribute* CreateUInt32(uint16_t type);
-  static StunUInt64Attribute* CreateUInt64(uint16_t type);
-  static StunByteStringAttribute* CreateByteString(uint16_t type);
-  static StunErrorCodeAttribute* CreateErrorCode();
-  static StunUInt16ListAttribute* CreateUnknownAttributes();
+  static std::unique_ptr<StunAddressAttribute> CreateAddress(uint16_t type);
+  static std::unique_ptr<StunXorAddressAttribute> CreateXorAddress(
+      uint16_t type);
+  static std::unique_ptr<StunUInt32Attribute> CreateUInt32(uint16_t type);
+  static std::unique_ptr<StunUInt64Attribute> CreateUInt64(uint16_t type);
+  static std::unique_ptr<StunByteStringAttribute> CreateByteString(
+      uint16_t type);
+  static std::unique_ptr<StunErrorCodeAttribute> CreateErrorCode();
+  static std::unique_ptr<StunUInt16ListAttribute> CreateUnknownAttributes();
 
  protected:
   StunAttribute(uint16_t type, uint16_t length);
@@ -412,7 +413,7 @@ class StunByteStringAttribute : public StunAttribute {
 // Implements STUN attributes that record an error code.
 class StunErrorCodeAttribute : public StunAttribute {
  public:
-  static const uint16_t MIN_SIZE = 4;
+  static const uint16_t MIN_SIZE;
   StunErrorCodeAttribute(uint16_t type, int code, const std::string& reason);
   StunErrorCodeAttribute(uint16_t type, uint16_t length);
   ~StunErrorCodeAttribute();