diff --git a/packager/media/base/playready_key_source.h b/packager/media/base/playready_key_source.h
index bfeed139d7..3eceb0c4dc 100644
--- a/packager/media/base/playready_key_source.h
+++ b/packager/media/base/playready_key_source.h
@@ -24,7 +24,7 @@ class PlayReadyKeySource : public KeySource {
   /// @param proteciton_systems_flags is the flags indicating which PSSH should
   ///        be included.
   PlayReadyKeySource(const std::string& server_url,
-                     int protection_scheme_flags);
+                     int protection_systems_flags);
   /// Creates a new PlayReadyKeySource from the given packaging information.
   /// @param server_url PlayReady packaging server url.
   /// @param client_cert_file absolute path to a client certificate.
@@ -37,7 +37,7 @@ class PlayReadyKeySource : public KeySource {
                      const std::string& client_cert_file,
                      const std::string& client_cert_private_key_file,
                      const std::string& client_cert_private_key_password,
-                     int protection_scheme_flags);
+                     int protection_systems_flags);
   ~PlayReadyKeySource() override;
 
   /// @name KeySource implementation overrides.
diff --git a/packager/media/base/playready_pssh_generator.cc b/packager/media/base/playready_pssh_generator.cc
index fe8f21ba36..e319b124c9 100644
--- a/packager/media/base/playready_pssh_generator.cc
+++ b/packager/media/base/playready_pssh_generator.cc
@@ -17,14 +17,12 @@
 #include "packager/base/strings/string_number_conversions.h"
 #include "packager/base/strings/string_util.h"
 #include "packager/media/base/buffer_writer.h"
-#include "packager/media/base/http_key_fetcher.h"
-#include "packager/media/base/key_source.h"
-#include "packager/media/base/playready_key_source.h"
 
 namespace shaka {
 namespace media {
 namespace {
 
+const uint8_t kPlayReadyPsshBoxVersion = 1;
 const std::string kPlayHeaderObject_4_1 =
     "<WRMHEADER "
     "xmlns=\"http://schemas.microsoft.com/DRM/2007/03/PlayReadyHeader\" "
@@ -128,8 +126,9 @@ Status GeneratePlayReadyPsshData(const std::vector<uint8_t>& key_id,
 }  // namespace
 
 PlayReadyPsshGenerator::PlayReadyPsshGenerator()
-    : system_id_(std::begin(kPlayReadySystemId), std::end(kPlayReadySystemId)) {
-}
+    : PsshGenerator(std::vector<uint8_t>(std::begin(kPlayReadySystemId),
+                                         std::end(kPlayReadySystemId)),
+                    kPlayReadyPsshBoxVersion) {}
 
 PlayReadyPsshGenerator::~PlayReadyPsshGenerator() {}
 
@@ -137,14 +136,6 @@ bool PlayReadyPsshGenerator::SupportMultipleKeys() {
   return false;
 }
 
-uint8_t PlayReadyPsshGenerator::PsshBoxVersion() const {
-  return 1;
-}
-
-const std::vector<uint8_t>& PlayReadyPsshGenerator::SystemId() const {
-  return system_id_;
-}
-
 base::Optional<std::vector<uint8_t>>
 PlayReadyPsshGenerator::GeneratePsshDataFromKeyIdAndKey(
     const std::vector<uint8_t>& key_id,
@@ -165,5 +156,6 @@ PlayReadyPsshGenerator::GeneratePsshDataFromKeyIds(
   NOTIMPLEMENTED();
   return base::nullopt;
 }
+
 }  // namespace media
 }  // namespace shaka
diff --git a/packager/media/base/playready_pssh_generator.h b/packager/media/base/playready_pssh_generator.h
index 1bbeb68e5a..d6e03c7201 100644
--- a/packager/media/base/playready_pssh_generator.h
+++ b/packager/media/base/playready_pssh_generator.h
@@ -7,10 +7,7 @@
 #ifndef MEDIA_BASE_PLAYREADY_PSSH_GENERATOR_H_
 #define MEDIA_BASE_PLAYREADY_PSSH_GENERATOR_H_
 
-#include <vector>
-
 #include "packager/media/base/pssh_generator.h"
-#include "testing/gtest/include/gtest/gtest_prod.h"
 
 namespace shaka {
 namespace media {
@@ -35,9 +32,6 @@ class PlayReadyPsshGenerator : public PsshGenerator {
   PlayReadyPsshGenerator(const PlayReadyPsshGenerator&) = delete;
 
   // PsshGenerator implemetation overrides.
-  uint8_t PsshBoxVersion() const override;
-
-  const std::vector<uint8_t>& SystemId() const override;
 
   base::Optional<std::vector<uint8_t>> GeneratePsshDataFromKeyIds(
       const std::vector<std::vector<uint8_t>>& key_ids) const override;
@@ -45,10 +39,6 @@ class PlayReadyPsshGenerator : public PsshGenerator {
   base::Optional<std::vector<uint8_t>> GeneratePsshDataFromKeyIdAndKey(
       const std::vector<uint8_t>& key_id,
       const std::vector<uint8_t>& key) const override;
-
-  std::vector<uint8_t> system_id_;
-
-  FRIEND_TEST(PsshGeneratorTest, GeneratePlayReadyPsshDataFromKeyIdAndKey);
 };
 
 }  // namespace media
diff --git a/packager/media/base/pssh_generator.cc b/packager/media/base/pssh_generator.cc
index 713998dffb..74458319c2 100644
--- a/packager/media/base/pssh_generator.cc
+++ b/packager/media/base/pssh_generator.cc
@@ -28,9 +28,11 @@ std::vector<uint8_t> CreatePsshBox(
 
 }  // namespace
 
-PsshGenerator::PsshGenerator() {}
+PsshGenerator::PsshGenerator(const std::vector<uint8_t>& system_id,
+                             uint8_t box_version)
+    : system_id_(system_id), box_version_(box_version) {}
 
-PsshGenerator::~PsshGenerator() {}
+PsshGenerator::~PsshGenerator() = default;
 
 Status PsshGenerator::GeneratePsshFromKeyIds(
     const std::vector<std::vector<uint8_t>>& key_ids,
@@ -41,9 +43,9 @@ Status PsshGenerator::GeneratePsshFromKeyIds(
     return Status(error::ENCRYPTION_FAILURE,
                   "Fail to generate PSSH data from multiple Key IDs.");
   }
-  info->system_id = SystemId();
+  info->system_id = system_id_;
   info->psshs =
-      CreatePsshBox(SystemId(), PsshBoxVersion(), key_ids, pssh_data.value());
+      CreatePsshBox(system_id_, box_version_, key_ids, pssh_data.value());
   return Status::OK;
 }
 
@@ -57,9 +59,9 @@ Status PsshGenerator::GeneratePsshFromKeyIdAndKey(
     return Status(error::ENCRYPTION_FAILURE,
                   "Fail to generate PSSH data from Key ID and Key.");
   }
-  info->system_id = SystemId();
+  info->system_id = system_id_;
   info->psshs =
-      CreatePsshBox(SystemId(), PsshBoxVersion(), {key_id}, pssh_data.value());
+      CreatePsshBox(system_id_, box_version_, {key_id}, pssh_data.value());
   return Status::OK;
 }
 
diff --git a/packager/media/base/pssh_generator.h b/packager/media/base/pssh_generator.h
index c96aeb89ca..fc8f87cbfe 100644
--- a/packager/media/base/pssh_generator.h
+++ b/packager/media/base/pssh_generator.h
@@ -17,12 +17,12 @@
 namespace shaka {
 namespace media {
 
-struct EncryptionKey;
-
 class PsshGenerator {
  public:
-  PsshGenerator();
-  virtual ~PsshGenerator() = 0;
+  /// @param system_id is the protection system id for the PSSH.
+  /// @param box_version specifies the version of the new PSSH box.
+  PsshGenerator(const std::vector<uint8_t>& system_id, uint8_t box_version);
+  virtual ~PsshGenerator();
 
   /// @return  whether the PSSH generates the PSSH box based on multiple key
   ///          IDs.
@@ -60,11 +60,8 @@ class PsshGenerator {
       const std::vector<uint8_t>& key_id,
       const std::vector<uint8_t>& key) const = 0;
 
-  /// Return the PSSH box version.
-  virtual uint8_t PsshBoxVersion() const = 0;
-
-  /// Return the System ID.
-  virtual const std::vector<uint8_t>& SystemId() const = 0;
+  std::vector<uint8_t> system_id_;
+  uint8_t box_version_ = 0;
 };
 
 }  // namespace media
diff --git a/packager/media/base/pssh_generator_unittest.cc b/packager/media/base/pssh_generator_unittest.cc
index 5fba63b7f9..c023edff8e 100644
--- a/packager/media/base/pssh_generator_unittest.cc
+++ b/packager/media/base/pssh_generator_unittest.cc
@@ -130,7 +130,7 @@ std::vector<uint8_t> GetTestKeyId2() {
 
 // TODO(hmchen): move each PsshGenerateTest for each specific key system
 // to each individual files (e.g., playready_pssh_generate_unittest.cc).
-TEST(PsshGeneratorTest, GeneratePlayReadyPsshDataFromKeyIds) {
+TEST(PsshGeneratorTest, GeneratePlayReadyPsshFromKeyIds) {
   const std::vector<std::vector<uint8_t>> kTestKeyIds = {GetTestKeyId1(),
                                                          GetTestKeyId2()};
   std::unique_ptr<PlayReadyPsshGenerator> playready_pssh_generator(
diff --git a/packager/media/base/raw_key_pssh_generator.cc b/packager/media/base/raw_key_pssh_generator.cc
index 05efc87545..6f602f4024 100644
--- a/packager/media/base/raw_key_pssh_generator.cc
+++ b/packager/media/base/raw_key_pssh_generator.cc
@@ -10,9 +10,14 @@
 
 namespace shaka {
 namespace media {
+namespace {
+const uint8_t kCommonSystemPsshBoxVersion = 1;
+}  // namespace
 
 RawKeyPsshGenerator::RawKeyPsshGenerator()
-    : system_id_(std::begin(kCommonSystemId), std::end(kCommonSystemId)) {}
+    : PsshGenerator(std::vector<uint8_t>(std::begin(kCommonSystemId),
+                                         std::end(kCommonSystemId)),
+                    kCommonSystemPsshBoxVersion) {}
 
 RawKeyPsshGenerator::~RawKeyPsshGenerator() {}
 
@@ -20,14 +25,6 @@ bool RawKeyPsshGenerator::SupportMultipleKeys() {
   return true;
 }
 
-uint8_t RawKeyPsshGenerator::PsshBoxVersion() const {
-  return 1;
-}
-
-const std::vector<uint8_t>& RawKeyPsshGenerator::SystemId() const {
-  return system_id_;
-}
-
 base::Optional<std::vector<uint8_t>>
 RawKeyPsshGenerator::GeneratePsshDataFromKeyIdAndKey(
     const std::vector<uint8_t>& key_id,
diff --git a/packager/media/base/raw_key_pssh_generator.h b/packager/media/base/raw_key_pssh_generator.h
index bdf1dd4989..8d169c67e2 100644
--- a/packager/media/base/raw_key_pssh_generator.h
+++ b/packager/media/base/raw_key_pssh_generator.h
@@ -7,12 +7,7 @@
 #ifndef MEDIA_BASE_RAW_KEY_PSSH_GENERATOR_H_
 #define MEDIA_BASE_RAW_KEY_PSSH_GENERATOR_H_
 
-#include <vector>
-
-#include "packager/media/base/key_source.h"
-#include "packager/media/base/protection_system_specific_info.h"
 #include "packager/media/base/pssh_generator.h"
-#include "testing/gtest/include/gtest/gtest_prod.h"
 
 namespace shaka {
 namespace media {
@@ -39,9 +34,6 @@ class RawKeyPsshGenerator : public PsshGenerator {
   RawKeyPsshGenerator(const RawKeyPsshGenerator&) = delete;
 
   // PsshGenerator implemetation overrides.
-  uint8_t PsshBoxVersion() const override;
-
-  const std::vector<uint8_t>& SystemId() const override;
 
   base::Optional<std::vector<uint8_t>> GeneratePsshDataFromKeyIds(
       const std::vector<std::vector<uint8_t>>& key_ids) const override;
@@ -49,8 +41,6 @@ class RawKeyPsshGenerator : public PsshGenerator {
   base::Optional<std::vector<uint8_t>> GeneratePsshDataFromKeyIdAndKey(
       const std::vector<uint8_t>& key_id,
       const std::vector<uint8_t>& key) const override;
-
-  std::vector<uint8_t> system_id_;
 };
 }  // namespace media
 }  // namespace shaka
diff --git a/packager/media/base/widevine_pssh_generator.cc b/packager/media/base/widevine_pssh_generator.cc
index fdc32b7bfe..7b0d827f4b 100644
--- a/packager/media/base/widevine_pssh_generator.cc
+++ b/packager/media/base/widevine_pssh_generator.cc
@@ -7,13 +7,18 @@
 #include "packager/media/base/widevine_pssh_generator.h"
 
 #include "packager/media/base/pssh_generator_util.h"
-#include "packager/media/base/widevine_key_source.h"
 
 namespace shaka {
 namespace media {
+namespace {
+// Use version 0 for backward compatibility.
+const uint8_t kWidevinePsshBoxVersion = 0;
+}  // namespace
 
 WidevinePsshGenerator::WidevinePsshGenerator()
-    : system_id_(std::begin(kWidevineSystemId), std::end(kWidevineSystemId)) {}
+    : PsshGenerator(std::vector<uint8_t>(std::begin(kWidevineSystemId),
+                                         std::end(kWidevineSystemId)),
+                    kWidevinePsshBoxVersion) {}
 
 WidevinePsshGenerator::~WidevinePsshGenerator() {}
 
@@ -21,15 +26,6 @@ bool WidevinePsshGenerator::SupportMultipleKeys() {
   return true;
 }
 
-uint8_t WidevinePsshGenerator::PsshBoxVersion() const {
-  // This is for backward compatibility.
-  return 0;
-}
-
-const std::vector<uint8_t>& WidevinePsshGenerator::SystemId() const {
-  return system_id_;
-}
-
 base::Optional<std::vector<uint8_t>>
 WidevinePsshGenerator::GeneratePsshDataFromKeyIds(
     const std::vector<std::vector<uint8_t>>& key_ids) const {
@@ -43,5 +39,6 @@ WidevinePsshGenerator::GeneratePsshDataFromKeyIdAndKey(
   NOTIMPLEMENTED();
   return base::nullopt;
 }
+
 }  // namespace media
 }  // namespace shaka
diff --git a/packager/media/base/widevine_pssh_generator.h b/packager/media/base/widevine_pssh_generator.h
index f6162c163d..a632fad015 100644
--- a/packager/media/base/widevine_pssh_generator.h
+++ b/packager/media/base/widevine_pssh_generator.h
@@ -7,11 +7,7 @@
 #ifndef MEDIA_BASE_WIDEVINE_PSSH_GENERATOR_H_
 #define MEDIA_BASE_WIDEVINE_PSSH_GENERATOR_H_
 
-#include <vector>
-
-#include "packager/media/base/key_source.h"
-#include "packager/media/base/protection_system_specific_info.h"
-#include "testing/gtest/include/gtest/gtest_prod.h"
+#include "packager/media/base/pssh_generator.h"
 
 namespace shaka {
 namespace media {
@@ -19,7 +15,6 @@ namespace media {
 const uint8_t kWidevineSystemId[] = {0xed, 0xef, 0x8b, 0xa9, 0x79, 0xd6,
                                      0x4a, 0xce, 0xa3, 0xc8, 0x27, 0xdc,
                                      0xd5, 0x1d, 0x21, 0xed};
-class WidevineKeySource;
 
 class WidevinePsshGenerator : public PsshGenerator {
  public:
@@ -36,9 +31,6 @@ class WidevinePsshGenerator : public PsshGenerator {
   WidevinePsshGenerator(const WidevinePsshGenerator&) = delete;
 
   // PsshGenerator implemetation overrides.
-  uint8_t PsshBoxVersion() const override;
-
-  const std::vector<uint8_t>& SystemId() const override;
 
   base::Optional<std::vector<uint8_t>> GeneratePsshDataFromKeyIds(
       const std::vector<std::vector<uint8_t>>& key_ids) const override;
@@ -46,8 +38,6 @@ class WidevinePsshGenerator : public PsshGenerator {
   base::Optional<std::vector<uint8_t>> GeneratePsshDataFromKeyIdAndKey(
       const std::vector<uint8_t>& key_id,
       const std::vector<uint8_t>& key) const override;
-
-  std::vector<uint8_t> system_id_;
 };
 
 }  // namespace media