Fix an issue that video is not seekable

When updating the ReadyState, HTMLMediaElement will immediately check the duration.
If at that time has_valid_metadata_ is false, we will return NaN.
So the has_valid_metadata_ has to be set before ReadyState is updated.

BUG=414499

Review URL: https://codereview.chromium.org/572803002

Cr-Commit-Position: refs/heads/master@{#294979}

content/renderer/media/android/webmediaplayer_android.cc

@@ -735,6 +735,10 @@ void WebMediaPlayerAndroid::OnMediaMetadataChanged(
     }
   }
 
+  // UpdateReadyState(WebMediaPlayer::ReadyStateHaveMetadata) will trigger a
+  // call to duration(), which checks |has_valid_metadata_|. so
+  // |has_valid_metadata_| has to be updated before calling UpdateReadyState().
+  has_valid_metadata_ = success;
   if (ready_state_ != WebMediaPlayer::ReadyStateHaveEnoughData) {
     UpdateReadyState(WebMediaPlayer::ReadyStateHaveMetadata);
     UpdateReadyState(WebMediaPlayer::ReadyStateHaveEnoughData);
@@ -745,8 +749,6 @@ void WebMediaPlayerAndroid::OnMediaMetadataChanged(
   if (success)
     OnVideoSizeChanged(width, height);
 
-  has_valid_metadata_ = success;
-
   if (need_to_signal_duration_changed)
     client_->durationChanged();
 }