media: Add Renderer::GetRendererType()

Currently RendererType is defined and tied to RendererFactorySelector
for media::Renderer creation/selection. This CL moves RendererType to
its own file and adds Renderer::GetRendererType() so it can be used
more boardly for logging and metrics.

This also helps make sure all media::Renderer implementations register a
RendererType so the list of RendererTypes is always up to date.

Bug: 1378123,1374532
Test: None since this is a trivial change
Change-Id: Ic81f72459241bb41e31deb2c1ccec17bc6d46fad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3984323
Reviewed-by: Thomas Guilbert <tguilbert@chromium.org>
Reviewed-by: Chris Bookholt <bookholt@chromium.org>
Reviewed-by: Alex Gough <ajgo@chromium.org>
Reviewed-by: Ted (Chromium) Meyer <tmathmeyer@chromium.org>
Auto-Submit: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Jordan Bayles <jophba@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1066579}

diff --git a/media/renderers/renderer_impl.h b/media/renderers/renderer_impl.h
index 9d250a3..0e30262 100644
--- a/media/renderers/renderer_impl.h
+++ b/media/renderers/renderer_impl.h

@@ -68,10 +68,11 @@
   base::TimeDelta GetMediaTime() final;
   void OnSelectedVideoTracksChanged(
       const std::vector<DemuxerStream*>& enabled_tracks,
-      base::OnceClosure change_completed_cb) override;
+      base::OnceClosure change_completed_cb) final;
   void OnEnabledAudioTracksChanged(
       const std::vector<DemuxerStream*>& enabled_tracks,
-      base::OnceClosure change_completed_cb) override;
+      base::OnceClosure change_completed_cb) final;
+  RendererType GetRendererType() final;
 
   // Helper functions for testing purposes. Must be called before Initialize().
   void DisableUnderflowForTesting();