[Backport] CVE-2021-30508: Heap buffer overflow in Media Feeds

Manual backport of patch originally reviewed on
https://chromium-review.googlesource.com/c/chromium/src/+/2847504:
Media Feeds: Disable Media Feeds and related features in M90

Media Feeds is deleted in M91 and later and is unused in previous
versions as well. There is a security issue with Media Feeds though, so
we'd like to force it to be disabled in previous versions, so this CL
turns it off for M90.

Bug: 1195340
Change-Id: I29e18be2abe4c1b4560d6324af3b6da93a97d947
Reviewed-by: dpapad <[email protected]>
Reviewed-by: Frank Liberato <[email protected]>
Commit-Queue: Tommy Steimel <[email protected]>
Cr-Commit-Position: refs/branch-heads/4430@{#1389}
Cr-Branched-From: e5ce7dc4f7518237b3d9bb93cccca35d25216cbe-refs/heads/master@{#857950}
Reviewed-by: Allan Sandfeld Jensen <[email protected]>

Author: steimelchrome

chromium/media/base/media_switches.cc

@@ -730,15 +730,15 @@ const base::Feature kMediaEngagementHTTPSOnly{
 
 // Enables Media Feeds to allow sites to provide specific recommendations for
 // users.
-const base::Feature kMediaFeeds{"MediaFeeds", base::FEATURE_ENABLED_BY_DEFAULT};
+const base::Feature kMediaFeeds{"MediaFeeds", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enables fetching Media Feeds periodically in the background.
 const base::Feature kMediaFeedsBackgroundFetching{
-    "MediaFeedsBackgroundFetching", base::FEATURE_ENABLED_BY_DEFAULT};
+    "MediaFeedsBackgroundFetching", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enables checking Media Feeds against safe search to prevent adult content.
 const base::Feature kMediaFeedsSafeSearch{"MediaFeedsSafeSearch",
-                                          base::FEATURE_ENABLED_BY_DEFAULT};
+                                          base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Send events to devtools rather than to chrome://media-internals
 const base::Feature kMediaInspectorLogging{"MediaInspectorLogging",