[eme] Enable Clear Key CDM to support 'cbcs' decryption

Now that AesDecryptor supports 'cbcs' decryption, update the
Clear Key CDM to do the same.

BUG=658026,835009
TEST=modified browser_test passes

Change-Id: Ie138d4b638d5d6493cb89368171adae5660486da
Reviewed-on: https://chromium-review.googlesource.com/1053172Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Commit-Queue: John Rummell <jrummell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557625}

chrome/browser/media/encrypted_media_browsertest.cc

@@ -803,9 +803,15 @@ IN_PROC_BROWSER_TEST_P(ECKEncryptedMediaTest, Playback_Encryption_CENS) {
 }
 
 IN_PROC_BROWSER_TEST_P(ECKEncryptedMediaTest, Playback_Encryption_CBCS) {
+  // 'cbcs' decryption is only supported on CDM 10 or later as long as
+  // the appropriate buildflag is enabled.
+  std::string expected_result =
+      GetCdmInterfaceVersion() >= 10 && BUILDFLAG(ENABLE_CBCS_ENCRYPTION_SCHEME)
+          ? media::kEnded
+          : media::kError;
   TestMp4EncryptionPlayback(kExternalClearKeyKeySystem,
                             "bear-640x360-v_frag-cbcs.mp4", kMp4Avc1VideoOnly,
-                            media::kError);
+                            expected_result);
 }
 
 #endif  // BUILDFLAG(USE_PROPRIETARY_CODECS)

chrome/common/chrome_content_client.cc

@@ -567,13 +567,11 @@ void ChromeContentClient::AddContentDecryptionModules(
       // Otherwise, it'll be treated as a sub-key-system of normal
       // kExternalClearKeyKeySystem. See MultipleCdmTypes test in
       // ECKEncryptedMediaTest.
-      // TODO(crbug.com/835009): Update when ECK supports more encryption
-      // schemes.
       cdms->push_back(content::CdmInfo(
           media::kClearKeyCdmDisplayName, media::kClearKeyCdmDifferentGuid,
           base::Version("0.1.0.0"), clear_key_cdm_path,
           media::kClearKeyCdmFileSystemId, {}, supports_persistent_license,
-          {media::EncryptionMode::kCenc},
+          {media::EncryptionMode::kCenc, media::EncryptionMode::kCbcs},
           kExternalClearKeyDifferentGuidTestKeySystem, false));
 
       // Supported codecs are hard-coded in ExternalClearKeyProperties.
@@ -581,7 +579,8 @@ void ChromeContentClient::AddContentDecryptionModules(
           media::kClearKeyCdmDisplayName, media::kClearKeyCdmGuid,
           base::Version("0.1.0.0"), clear_key_cdm_path,
           media::kClearKeyCdmFileSystemId, {}, supports_persistent_license,
-          {media::EncryptionMode::kCenc}, kExternalClearKeyKeySystem, true));
+          {media::EncryptionMode::kCenc, media::EncryptionMode::kCbcs},
+          kExternalClearKeyKeySystem, true));
     }
 #endif  // BUILDFLAG(ENABLE_LIBRARY_CDMS)
   }

media/cdm/library_cdm/clear_key_cdm/clear_key_cdm.cc

@@ -21,6 +21,7 @@
 #include "media/base/cdm_key_information.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/decrypt_config.h"
+#include "media/base/encryption_pattern.h"
 #include "media/cdm/api/content_decryption_module_ext.h"
 #include "media/cdm/json_web_key.h"
 #include "media/cdm/library_cdm/cdm_host_proxy.h"
@@ -95,23 +96,32 @@ static scoped_refptr<media::DecoderBuffer> CopyDecoderBufferFrom(
   output_buffer->set_timestamp(
       base::TimeDelta::FromMicroseconds(input_buffer.timestamp));
 
-  // TODO(crbug.com/658026): Support other schemes.
-  if (input_buffer.encryption_scheme == cdm::EncryptionScheme::kCenc) {
-    DCHECK_GT(input_buffer.iv_size, 0u);
-    DCHECK_GT(input_buffer.key_id_size, 0u);
-    std::vector<media::SubsampleEntry> subsamples;
-    for (uint32_t i = 0; i < input_buffer.num_subsamples; ++i) {
-      subsamples.push_back(
-          media::SubsampleEntry(input_buffer.subsamples[i].clear_bytes,
-                                input_buffer.subsamples[i].cipher_bytes));
-    }
+  if (input_buffer.encryption_scheme == cdm::EncryptionScheme::kUnencrypted)
+    return output_buffer;
+
+  DCHECK_GT(input_buffer.iv_size, 0u);
+  DCHECK_GT(input_buffer.key_id_size, 0u);
+  std::vector<media::SubsampleEntry> subsamples;
+  for (uint32_t i = 0; i < input_buffer.num_subsamples; ++i) {
+    subsamples.push_back(
+        media::SubsampleEntry(input_buffer.subsamples[i].clear_bytes,
+                              input_buffer.subsamples[i].cipher_bytes));
+  }
 
+  const std::string key_id_string(
+      reinterpret_cast<const char*>(input_buffer.key_id),
+      input_buffer.key_id_size);
+  const std::string iv_string(reinterpret_cast<const char*>(input_buffer.iv),
+                              input_buffer.iv_size);
+  if (input_buffer.encryption_scheme == cdm::EncryptionScheme::kCenc) {
     output_buffer->set_decrypt_config(media::DecryptConfig::CreateCencConfig(
-        std::string(reinterpret_cast<const char*>(input_buffer.key_id),
-                    input_buffer.key_id_size),
-        std::string(reinterpret_cast<const char*>(input_buffer.iv),
-                    input_buffer.iv_size),
-        subsamples));
+        key_id_string, iv_string, subsamples));
+  } else {
+    DCHECK_EQ(input_buffer.encryption_scheme, cdm::EncryptionScheme::kCbcs);
+    output_buffer->set_decrypt_config(media::DecryptConfig::CreateCbcsConfig(
+        key_id_string, iv_string, subsamples,
+        media::EncryptionPattern(input_buffer.pattern.crypt_byte_block,
+                                 input_buffer.pattern.skip_byte_block)));
   }
 
   return output_buffer;
@@ -362,36 +372,6 @@ namespace media {
 
 namespace {
 
-bool IsSupportedConfigEncryptionScheme(cdm::EncryptionScheme scheme) {
-  // TODO(crbug.com/658026): Support other decryption schemes.
-  switch (scheme) {
-    case cdm::EncryptionScheme::kUnencrypted:
-    case cdm::EncryptionScheme::kCenc:
-      return true;
-    case cdm::EncryptionScheme::kCbcs:
-      return false;
-  }
-
-  NOTREACHED();
-  return false;
-}
-
-bool IsSupportedBufferEncryptionScheme(cdm::EncryptionScheme scheme,
-                                       cdm::Pattern pattern) {
-  // TODO(crbug.com/658026): Support other decryption schemes.
-  switch (scheme) {
-    case cdm::EncryptionScheme::kUnencrypted:
-      return true;
-    case cdm::EncryptionScheme::kCenc:
-      return pattern.crypt_byte_block == 0 && pattern.skip_byte_block == 0;
-    case cdm::EncryptionScheme::kCbcs:
-      return false;
-  }
-
-  NOTREACHED();
-  return false;
-}
-
 cdm::InputBuffer_2 ToInputBuffer_2(cdm::InputBuffer_1 encrypted_buffer) {
   cdm::InputBuffer_2 buffer = {};
   buffer.data = encrypted_buffer.data;
@@ -707,11 +687,6 @@ cdm::Status ClearKeyCdm::InitializeAudioDecoder(
   if (key_system_ == kExternalClearKeyDecryptOnlyKeySystem)
     return cdm::kInitializationError;
 
-  if (!IsSupportedConfigEncryptionScheme(
-          audio_decoder_config.encryption_scheme)) {
-    return cdm::kInitializationError;
-  }
-
 #if defined(CLEAR_KEY_CDM_USE_FFMPEG_DECODER)
   if (!audio_decoder_)
     audio_decoder_.reset(
@@ -744,11 +719,6 @@ cdm::Status ClearKeyCdm::InitializeVideoDecoder(
   if (key_system_ == kExternalClearKeyDecryptOnlyKeySystem)
     return cdm::kInitializationError;
 
-  if (!IsSupportedConfigEncryptionScheme(
-          video_decoder_config.encryption_scheme)) {
-    return cdm::kInitializationError;
-  }
-
   if (video_decoder_ && video_decoder_->is_initialized()) {
     DCHECK(!video_decoder_->is_initialized());
     return cdm::kInitializationError;
@@ -894,11 +864,6 @@ cdm::Status ClearKeyCdm::DecryptToMediaDecoderBuffer(
     scoped_refptr<DecoderBuffer>* decrypted_buffer) {
   DCHECK(decrypted_buffer);
 
-  if (!IsSupportedBufferEncryptionScheme(encrypted_buffer.encryption_scheme,
-                                         encrypted_buffer.pattern)) {
-    return cdm::kDecryptError;
-  }
-
   scoped_refptr<DecoderBuffer> buffer = CopyDecoderBufferFrom(encrypted_buffer);
 
   // EOS and unencrypted streams can be returned as-is.