fix(blur) disable blur button if camera is off

react/features/blur/components/VideoBlurButton.js

 import { connect } from '../../base/redux';
 import { AbstractButton } from '../../base/toolbox/components';
 import type { AbstractButtonProps } from '../../base/toolbox/components';
+import { isLocalCameraTrackMuted } from '../../base/tracks';
 import { toggleBlurEffect } from '../actions';
 
 /**
      */
     _isVideoBlurred: boolean,
 
+    /**
+     * Whether video is currently muted or not.
+     */
+    _videoMuted: boolean,
+
     /**
      * The redux {@code dispatch} function.
      */
     _isToggled() {
         return this.props._isVideoBlurred;
     }
+
+    /**
+     * Returns {@code boolean} value indicating if disabled state is
+     * enabled or not.
+     *
+     * @protected
+     * @returns {boolean}
+     */
+    _isDisabled() {
+        return this.props._videoMuted;
+    }
 }
 
 /**
  * }}
  */
 function _mapStateToProps(state): Object {
+    const tracks = state['features/base/tracks'];
+
     return {
-        _isVideoBlurred: Boolean(state['features/blur'].blurEnabled)
+        _isVideoBlurred: Boolean(state['features/blur'].blurEnabled),
+        _videoMuted: isLocalCameraTrackMuted(tracks)
     };
 }
 
 export default translate(connect(_mapStateToProps)(VideoBlurButton));
+