media: Add kHardwareSecureDecryption feature

For now this is used as the flag to enable hardware secure decryption
support on Windows while it's still under development.

Added a TODO to apply this flag to Android and ChromeOS where hardware
secure decryption is already supported.

Bug: 848532
Test: No functionality change.
Change-Id: Ie263008ace5f8da5da1ab94acf22485046a79b7d
Reviewed-on: https://chromium-review.googlesource.com/1103283
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: John Rummell <jrummell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568316}

chrome/renderer/media/chrome_key_systems.cc

@@ -237,17 +237,33 @@ static void AddWidevine(
     return;
   }
 
+  // Codecs and encryption schemes.
   auto supported_codecs = GetSupportedCodecs(capability->video_codecs);
   const auto& supported_encryption_schemes = capability->encryption_schemes;
-
-  // On ChromeOS, we do not have real hardware secure codecs. But this does not
-  // affect HW_SECURE* support since the support doesn't require hardware secure
-  // codecs. See WidevineKeySystemProperties::GetRobustnessConfigRule().
   auto supported_hw_secure_codecs =
       GetSupportedCodecs(capability->hw_secure_video_codecs);
 
-  // TODO(crbug.com/853261): Support capability->hw_secure_encryption_schemes.
+  // TODO(crbug.com/853261): Support capability->hw_secure_encryption_schemes
+  // and pass it into WidevineKeySystemProperties.
+
+  // Robustness.
+  using Robustness = cdm::WidevineKeySystemProperties::Robustness;
+  auto max_audio_robustness = Robustness::SW_SECURE_CRYPTO;
+  auto max_video_robustness = Robustness::SW_SECURE_DECODE;
+
+#if defined(OS_CHROMEOS)
+  // On ChromeOS, we support HW_SECURE_ALL even without hardware secure codecs.
+  // See WidevineKeySystemProperties::GetRobustnessConfigRule().
+  max_audio_robustness = Robustness::HW_SECURE_ALL;
+  max_video_robustness = Robustness::HW_SECURE_ALL;
+#else
+  if (base::FeatureList::IsEnabled(media::kHardwareSecureDecryption)) {
+    max_audio_robustness = Robustness::HW_SECURE_CRYPTO;
+    max_video_robustness = Robustness::HW_SECURE_ALL;
+  }
+#endif
 
+  // Session types.
   bool cdm_supports_temporary_session = base::ContainsValue(
       capability->session_types, media::CdmSessionType::TEMPORARY_SESSION);
   if (!cdm_supports_temporary_session) {
@@ -260,28 +276,21 @@ static void AddWidevine(
                           media::CdmSessionType::PERSISTENT_LICENSE_SESSION);
   auto persistent_license_support =
       GetPersistentLicenseSupport(cdm_supports_persistent_license);
+  auto persistent_release_message_support =
+      EmeSessionTypeSupport::NOT_SUPPORTED;
 
-  using Robustness = cdm::WidevineKeySystemProperties::Robustness;
+  // Others.
+  auto persistent_state_support = EmeFeatureSupport::REQUESTABLE;
+  auto distinctive_identifier_support = EmeFeatureSupport::NOT_SUPPORTED;
+#if defined(OS_CHROMEOS)
+  distinctive_identifier_support = EmeFeatureSupport::REQUESTABLE;
+#endif
 
-  // TODO(xhwang/jrummell): Parse hw_secure_encryption_schemes.
   concrete_key_systems->emplace_back(new cdm::WidevineKeySystemProperties(
       supported_encryption_schemes, supported_codecs,
-      supported_hw_secure_codecs,
-#if defined(OS_CHROMEOS)
-      Robustness::HW_SECURE_ALL,             // Maximum audio robustness.
-      Robustness::HW_SECURE_ALL,             // Maximum video robustness.
-      persistent_license_support,            // Persistent-license.
-      EmeSessionTypeSupport::NOT_SUPPORTED,  // Persistent-release-message.
-      EmeFeatureSupport::REQUESTABLE,        // Persistent state.
-      EmeFeatureSupport::REQUESTABLE));      // Distinctive identifier.
-#else                                        // Desktop
-      Robustness::SW_SECURE_CRYPTO,          // Maximum audio robustness.
-      Robustness::SW_SECURE_DECODE,          // Maximum video robustness.
-      persistent_license_support,            // persistent-license.
-      EmeSessionTypeSupport::NOT_SUPPORTED,  // persistent-release-message.
-      EmeFeatureSupport::REQUESTABLE,        // Persistent state.
-      EmeFeatureSupport::NOT_SUPPORTED));    // Distinctive identifier.
-#endif                                       // defined(OS_CHROMEOS)
+      supported_hw_secure_codecs, max_audio_robustness, max_video_robustness,
+      persistent_license_support, persistent_release_message_support,
+      persistent_state_support, distinctive_identifier_support));
 }
 #endif  // defined(WIDEVINE_CDM_AVAILABLE)
 #endif  // BUILDFLAG(ENABLE_LIBRARY_CDMS)

content/browser/media/key_system_support_impl.cc

@@ -7,12 +7,14 @@
 #include <vector>
 
 #include "base/containers/flat_set.h"
+#include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_functions.h"
 #include "content/public/browser/cdm_registry.h"
 #include "content/public/common/cdm_info.h"
 #include "media/base/key_system_names.h"
 #include "media/base/key_systems.h"
+#include "media/base/media_switches.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
 
 namespace content {
@@ -77,7 +79,11 @@ void KeySystemSupportImpl::IsKeySystemSupported(
   capability->encryption_schemes =
       std::vector<media::EncryptionMode>(schemes.begin(), schemes.end());
 
-  // TODO(xhwang): Populate hw_secure* fields on Windows.
+  if (base::FeatureList::IsEnabled(media::kHardwareSecureDecryption)) {
+    // TODO(xhwang): Call into GetContentClient()->browser() to get key system
+    // specific hardware secure decryption capability on Windows.
+    NOTIMPLEMENTED();
+  }
 
   // Temporary session is always supported.
   // TODO(xhwang): Populate this from CdmInfo.

media/base/media_switches.cc

@@ -321,6 +321,13 @@ const base::Feature kVideoBlitColorAccuracy{"video-blit-color-accuracy",
 const base::Feature kExternalClearKeyForTesting{
     "ExternalClearKeyForTesting", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Enables hardware secure decryption if supported by hardware and CDM.
+// TODO(xhwang): Currently this is only used for development of new features.
+// Apply this to Android and ChromeOS as well where hardware secure decryption
+// is already available.
+const base::Feature kHardwareSecureDecryption{
+    "HardwareSecureDecryption", base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Enables low-delay video rendering in media pipeline on "live" stream.
 const base::Feature kLowDelayVideoRenderingOnLiveStream{
     "low-delay-video-rendering-on-live-stream",

media/base/media_switches.h

@@ -109,6 +109,7 @@ MEDIA_EXPORT extern const base::Feature kBackgroundVideoPauseOptimization;
 MEDIA_EXPORT extern const base::Feature kBackgroundVideoTrackOptimization;
 MEDIA_EXPORT extern const base::Feature kD3D11VideoDecoder;
 MEDIA_EXPORT extern const base::Feature kExternalClearKeyForTesting;
+MEDIA_EXPORT extern const base::Feature kHardwareSecureDecryption;
 MEDIA_EXPORT extern const base::Feature kLowDelayVideoRenderingOnLiveStream;
 MEDIA_EXPORT extern const base::Feature kMediaCastOverlayButton;
 MEDIA_EXPORT extern const base::Feature kRecordMediaEngagementScores;