PlayReady on Android requires hardware secure codecs

Today we always use hardware secure codecs for non-Widevine key systems.
This is DCHECKed in AndroidCdmFactory::Create() when we create
MediaDrmBridge for PlayReady key system. Also, in
MediaDrmBridge::IsSecureCodecRequired(), we always return true for
non-Widevine key systems including PlayReady.

This CL updates PlayReadyKeySystemProperties to always return
HW_SECURE_CODECS_REQUIRED in GetRobustnessConfigRule() for PlayReady key
system to make everything consistent.

BUG=577777

Change-Id: I7b94f5dc22fb8c98d7e17709f767c766ebd54858
Reviewed-on: https://chromium-review.googlesource.com/531855
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478835}

chromecast/renderer/media/key_systems_cast.cc

@@ -77,8 +77,17 @@ class PlayReadyKeySystemProperties : public ::media::KeySystemProperties {
   EmeConfigRule GetRobustnessConfigRule(
       EmeMediaType media_type,
       const std::string& requested_robustness) const override {
-    return requested_robustness.empty() ? EmeConfigRule::SUPPORTED
-                                        : EmeConfigRule::NOT_SUPPORTED;
+    if (requested_robustness.empty()) {
+#if defined(OS_ANDROID)
+      return EmeConfigRule::HW_SECURE_CODECS_REQUIRED;
+#else
+      return EmeConfigRule::SUPPORTED;
+#endif
+    }
+
+    // Cast-specific PlayReady implementation does not currently recognize or
+    // support non-empty robustness strings.
+    return EmeConfigRule::NOT_SUPPORTED;
   }
 
   EmeSessionTypeSupport GetPersistentLicenseSessionSupport() const override {