Drop DecryptConfig::data_offset_.

media/webm/webm_crypto_helpers.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/webm/webm_crypto_helpers.h"
 
 #include "base/logging.h"
 #include "base/sys_byteorder.h"
 #include "media/base/decrypt_config.h"
 #include "media/webm/webm_constants.h"
 
 namespace media {
 namespace {
 
 // Generates a 16 byte CTR counter block. The CTR counter block format is a
 // CTR IV appended with a CTR block counter. |iv| is an 8 byte CTR IV.
 // |iv_size| is the size of |iv| in btyes. Returns a string of
 // kDecryptionKeySize bytes.
 std::string GenerateWebMCounterBlock(const uint8* iv, int iv_size) {
   std::string counter_block(reinterpret_cast<const char*>(iv), iv_size);
   counter_block.append(DecryptConfig::kDecryptionKeySize - iv_size, 0);
   return counter_block;
 }
 
 }  // namespace anonymous
 
-scoped_ptr<DecryptConfig> WebMCreateDecryptConfig(
-    const uint8* data, int data_size,
-    const uint8* key_id, int key_id_size) {
+bool WebMCreateDecryptConfig(const uint8* data, int data_size,
+                             const uint8* key_id, int key_id_size,
+                             scoped_ptr<DecryptConfig>* decrypt_config,

[DaleCurtis, 2014/01/02 19:31:09]

Just make it a regular pointer? This method shouldn't really care how the caller
allocates the DecryptConfig.

[xhwang, 2014/01/08 00:43:36]

Hmm, we have "new" on l.53. If we return a regular pointer, the caller has to
remember to "delete" it, or wrap it in a scoped_ptr<>. I like to wrap it
immediately so that the ownership is super clear. Maybe I missed something?

+                             int* data_offset) {
   if (data_size < kWebMSignalByteSize) {
     DVLOG(1) << "Got a block from an encrypted stream with no data.";
-    return scoped_ptr<DecryptConfig>();
+    return false;
   }
 
   uint8 signal_byte = data[0];
   int frame_offset = sizeof(signal_byte);
 
   // Setting the DecryptConfig object of the buffer while leaving the
   // initialization vector empty will tell the decryptor that the frame is
   // unencrypted.
   std::string counter_block;
 
   if (signal_byte & kWebMFlagEncryptedFrame) {
     if (data_size < kWebMSignalByteSize + kWebMIvSize) {
       DVLOG(1) << "Got an encrypted block with not enough data " << data_size;
-      return scoped_ptr<DecryptConfig>();
+      return false;
     }
     counter_block = GenerateWebMCounterBlock(data + frame_offset, kWebMIvSize);
     frame_offset += kWebMIvSize;
   }
 
-  scoped_ptr<DecryptConfig> config(new DecryptConfig(
+  decrypt_config->reset(new DecryptConfig(
       std::string(reinterpret_cast<const char*>(key_id), key_id_size),
       counter_block,
-      frame_offset,
       std::vector<SubsampleEntry>()));
-  return config.Pass();
+  *data_offset = frame_offset;
+
+  return true;
 }
 
 }  // namespace media