media: Add External Clear Key content browser test on Android

media/base/key_systems.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/base/key_systems.h"
 
 #include <stddef.h>
 
 #include <memory>
 
@@ skipping 400 matching lines @@
     // Distinctive identifiers and persistent state can only be reliably blocked
     // (and therefore be safely configurable) for Pepper-hosted key systems. For
     // other platforms, (except for the AES decryptor) assume that the CDM can
     // and will do anything.
     bool can_block = properties->UseAesDecryptor();
 #if defined(ENABLE_PEPPER_CDMS)
     DCHECK_EQ(properties->UseAesDecryptor(),
               properties->GetPepperType().empty());
     if (!properties->GetPepperType().empty())
       can_block = true;
+#elif defined(OS_ANDROID)
+    if (IsExternalClearKey(properties->GetKeySystemName()))
+      can_block = true;

[ddorwin, 2016/09/14 01:06:27]

Please add a comment. Maybe above with the general description.
We may also want to note that this is only a policy check and not a security
check since AesDecryptor runs in a different process, albeit the trusted browser
process.

[xhwang, 2016/09/16 18:50:17]

Done.

 #endif
     if (!can_block) {
       DCHECK(properties->GetDistinctiveIdentifierSupport() ==
              EmeFeatureSupport::ALWAYS_ENABLED);
       DCHECK(properties->GetPersistentStateSupport() ==
              EmeFeatureSupport::ALWAYS_ENABLED);
     }
 
     DCHECK_EQ(key_system_properties_map_.count(properties->GetKeySystemName()),
               0u)
@@ skipping 296 matching lines @@
                                uint32_t mask) {
   KeySystemsImpl::GetInstance()->AddCodecMask(media_type, codec, mask);
 }
 
 MEDIA_EXPORT void AddMimeTypeCodecMask(const std::string& mime_type,
                                        uint32_t mask) {
   KeySystemsImpl::GetInstance()->AddMimeTypeCodecMask(mime_type, mask);
 }
 
 }  // namespace media