For Clear Key video, the video is decrypted in the renderer process and we are not using MediaDrmBridge. So this seems to be a MediaCodec/Decoder issue.

If the video stays at that resolution, could it be because you don't have sufficient bandwidth to play a higher resolution?  Or that the player thinks this is true?

In a debugger, you can check this to get Shaka's current bandwidth estimate:

shakaDemo.localPlayer_.getStats().estimatedBandwidth

More generally getStats() has lots of information about the decisions the player is making.

Also, I just noticed, this is not using Clear Key.  The content is not encrypted.

Joey,
I don't think bandwidth is the cause of this bug. I am running on the same device at the same time using Chrome 62, the resolution is upgraded as expected without problem.

Frank, I have the device for you to use if need.

Yining,

It's entirely possible that bandwidth is not the issue.  However, since Shaka Player makes streaming and adaptation decisions based on bandwidth, it seems like it's important to know what Shaka's bandwidth estimate is.  I highly recommend checking this out.

In MediaSource-based applications, JavaScript is responsible for fetching media segments and feeding them to the browser.  It's hard to imagine how the resolution would stay low if the application was making a decision to fetch HD.

i'll try to repro on my 5x.  would be good to know if it's specific to the device or not.

I tried one more time on the same device, surprisely the issue NOT repro anymore. resolution can move upward as playback proceed as expected. It may be because of bandwidth as joey said.
I'll resolve this bug as won't fix.