media: Create MediaCrypto upon MediaDrmBridge creation.

media/base/android/media_drm_bridge.h

 // Copyright (c) 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.
 
 #ifndef MEDIA_BASE_ANDROID_MEDIA_DRM_BRIDGE_H_
 #define MEDIA_BASE_ANDROID_MEDIA_DRM_BRIDGE_H_
 
 #include <jni.h>
 #include <stdint.h>
 #include <string>
@@ skipping 226 matching lines @@
       JNIEnv* env,
       const base::android::JavaParamRef<jobject>&,
       bool success);
 
  private:
   // For DeleteSoon() in DeleteOnCorrectThread().
   friend class base::DeleteHelper<MediaDrmBridge>;
 
   // Constructs a MediaDrmBridge for |scheme_uuid| and |security_level|. The
   // default security level will be used if |security_level| is
-  // SECURITY_LEVEL_DEFAULT.
+  // SECURITY_LEVEL_DEFAULT. Sessions should not be created if session callbacks
+  // are null.
   MediaDrmBridge(const std::vector<uint8_t>& scheme_uuid,
                  SecurityLevel security_level,
                  const CreateFetcherCB& create_fetcher_cb,
                  const SessionMessageCB& session_message_cb,
                  const SessionClosedCB& session_closed_cb,
                  const LegacySessionErrorCB& legacy_session_error_cb,
                  const SessionKeysChangeCB& session_keys_change_cb,
                  const SessionExpirationUpdateCB& session_expiration_update_cb);
 
   ~MediaDrmBridge() override;
@@ skipping 58 matching lines @@
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<MediaDrmBridge> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaDrmBridge);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_ANDROID_MEDIA_DRM_BRIDGE_H_