Fixup tab capture and cast streaming OWNERS.

1. Removed people long-gone from the project (by several years).
2. Added xjz@ for cast streaming files.
3. Fixed/Added "# COMPONENT" comments to help redirect new crbugs.

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: I1a549a4f85e76f563a162263e90268de57daddab
Reviewed-on: https://chromium-review.googlesource.com/1065089Reviewed-by: Xiangjun Zhang <xjz@chromium.org>
Reviewed-by: John Rummell <jrummell@chromium.org>
Commit-Queue: Yuri Wiitala <miu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560320}

chrome/browser/extensions/api/cast_streaming/OWNERS

-hubbe@chromium.org
 miu@chromium.org
+xjz@chromium.org
 
 # COMPONENT: Internals>Cast>Streaming

chrome/browser/extensions/api/tab_capture/OWNERS

-hubbe@chromium.org
-justinlin@chromium.org
 miu@chromium.org
 
-# COMPONENT: UI>Browser>TabCapture
+# COMPONENT: Blink>GetUserMedia>Tab

chrome/browser/media/OWNERS

@@ -2,9 +2,9 @@ file://media/OWNERS
 sergeyu@chromium.org
 tommi@chromium.org
 
-# For Cast streaming changes.
-per-file cast_*=hubbe@chromium.org
+# For Cast-related changes.
 per-file cast_*=miu@chromium.org
+per-file cast_*=xjz@chromium.org
 
 # For Media Engagement
 per-file media_engagement*=beccahughes@chromium.org

chrome/renderer/media/OWNERS

@@ -2,8 +2,8 @@ file://media/OWNERS
 sergeyu@chromium.org
 tommi@chromium.org
 
-# For Cast streaming changes.
-per-file cast_*=hubbe@chromium.org
+# For Cast-related changes.
 per-file cast_*=miu@chromium.org
+per-file cast_*=xjz@chromium.org
 
 # COMPONENT: Internals>Media

components/viz/service/frame_sinks/video_capture/OWNERS

 miu@chromium.org
+
+# COMPONENT: Internals>Media>ScreenCapture

content/browser/media/capture/OWNERS

@@ -8,5 +8,4 @@ per-file desktop_capture_device_unittest.cc=zijiehe@chromium.org
 
 per-file image_capture*=mcasas@chromium.org
 
-# TEAM: media-capture-and-streams@grotations.appspotmail.com
-# COMPONENT: Blink>GetUserMedia
+# COMPONENT: Internals>Media>ScreenCapture

media/capture/content/OWNERS

 miu@chromium.org
 
-# COMPONENT: UI>Browser>TabCapture
+# COMPONENT: Internals>Media>ScreenCapture

media/cast/OWNERS

-hubbe@chromium.org
 miu@chromium.org
+xjz@chromium.org
 
 # COMPONENT: Internals>Cast>Streaming

media/remoting/OWNERS

 erickung@chromium.org
 miu@chromium.org
+xjz@chromium.org
 
 # COMPONENT: Internals>Cast>Streaming