Bug 1846848 - part8 : display clear lead support. r=jolin,fluent-reviewers,flod

Differential Revision: https://phabricator.services.mozilla.com/D195058

dom/chrome-webidl/ChromeUtils.webidl

@@ -1099,4 +1099,5 @@ dictionary LibcConstants {
 dictionary CDMInformation {
   required DOMString keySystemName;
   required DOMString capabilities;
+  required boolean clearlead;
 };

dom/media/eme/EMEUtils.cpp

@@ -188,4 +188,21 @@ void MFCDMCapabilitiesIPDLToKeySystemConfig(
 }
 #endif
 
+bool DoesKeySystemSupportClearLead(const nsAString& aKeySystem) {
+  // I believe that Widevine L3 supports clear-lead, but I couldn't find any
+  // official documentation to prove that. The only one I can find is that Shaka
+  // player mentions the clear lead feature. So we expect L3 should have that as
+  // well. But for HWDRM, Widevine L1 and SL3000 needs to rely on special checks
+  // to know whether clearlead is supported. That will be implemented by
+  // querying for special key system names.
+  // https://shaka-project.github.io/shaka-packager/html/documentation.html
+#ifdef MOZ_WMF_CDM
+  // TODO : implement new key system for PlayReady.
+  if (aKeySystem.EqualsLiteral(kWidevineExperiment2KeySystemName)) {
+    return true;
+  }
+#endif
+  return aKeySystem.EqualsLiteral(kWidevineKeySystemName);
+}
+
 }  // namespace mozilla

dom/media/eme/EMEUtils.h

@@ -91,6 +91,8 @@ void MFCDMCapabilitiesIPDLToKeySystemConfig(
     const MFCDMCapabilitiesIPDL& aCDMConfig, KeySystemConfig& aKeySystemConfig);
 #endif
 
+bool DoesKeySystemSupportClearLead(const nsAString& aKeySystem);
+
 }  // namespace mozilla
 
 #endif  // EME_LOG_H_

dom/media/eme/KeySystemConfig.cpp

@@ -231,6 +231,7 @@ void KeySystemConfig::GetGMPKeySystemConfigs(dom::Promise* aPromise) {
       MOZ_ASSERT(keySystemConfigs.Length() == cdmInfo.Length());
       info->mKeySystemName = name;
       info->mCapabilities = keySystemConfigs.LastElement().GetDebugInfo();
+      info->mClearlead = DoesKeySystemSupportClearLead(name);
     }
   }
   aPromise->MaybeResolve(cdmInfo);

ipc/glue/UtilityAudioDecoderChild.cpp

@@ -213,6 +213,8 @@ void UtilityAudioDecoderChild::GetKeySystemCapabilities(
           KeySystemConfig config;
           MFCDMCapabilitiesIPDLToKeySystemConfig(capabilities, config);
           info->mCapabilities = config.GetDebugInfo();
+          info->mClearlead =
+              DoesKeySystemSupportClearLead(info->mKeySystemName);
         }
         promise->MaybeResolve(cdmInfo);
       },

toolkit/content/aboutSupport.js

@@ -1177,6 +1177,7 @@ var snapshotFormatters = {
         $.new("td", getVideoRobustness(rvArray)),
         $.new("td", getAudioRobustness(rvArray)),
         $.new("td", getCapabilities(rvArray)),
+        $.new("td", cdmInfo.clearlead ? "Yes" : "No"),
       ]);
     }
 

toolkit/content/aboutSupport.xhtml

@@ -567,13 +567,14 @@
 
         <tbody id="media-content-decryption-modules-tbody">
           <tr>
-            <th colspan="4" class="title-column" data-l10n-id="media-content-decryption-modules-title"/>
+            <th colspan="5" class="title-column" data-l10n-id="media-content-decryption-modules-title"/>
           </tr>
           <tr>
             <th data-l10n-id="media-key-system-name"/>
             <th data-l10n-id="media-video-robustness"/>
             <th data-l10n-id="media-audio-robustness"/>
             <th data-l10n-id="media-cdm-capabilities"/>
+            <th data-l10n-id="media-cdm-clear-lead"/>
           </tr>
         </tbody>
 

toolkit/locales/en-US/toolkit/about/aboutSupport.ftl

@@ -201,6 +201,10 @@ media-key-system-name = Key System Name
 media-video-robustness = Video Robustness
 media-audio-robustness = Audio Robustness
 media-cdm-capabilities = Capabilities
+# Clear Lead isn't defined in the spec, which means the the first few seconds
+# are not encrypted. It allows playback to start without having to wait for
+# license response, improving video start time and user experience.
+media-cdm-clear-lead = Clear Lead
 
 ##