Disable the backdrop-filter feature by default for Android

With this CL, backdrop-filter is disabled for all of Android. It
will be (first) enabled via Finch for Android non-Webview platforms
and all other platforms just in case. This was suggested as a good
course of action rather than relying only on the Finch system to
disable the feature for Webview. See the discussion in
crbug.com/997290.

Bug: 997290
Change-Id: I7996cc674114701fb1a833f859a9a18e397327ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1772280Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Mason Freed <masonfreed@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691727}

third_party/blink/common/features.cc

@@ -64,8 +64,18 @@ const base::Feature kJankTrackingSweepLine{"JankTrackingSweepLine",
                                            base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enable a new CSS property called backdrop-filter.
-const base::Feature kCSSBackdropFilter{"CSSBackdropFilter",
-                                       base::FEATURE_ENABLED_BY_DEFAULT};
+const base::Feature kCSSBackdropFilter {
+  "CSSBackdropFilter",
+#if defined(OS_ANDROID)
+      // There are two bugs in the backdrop-filter feature for Android Webview
+      // only (crbug.com/990535 and crbug.com/991869). Because there is no
+      // compile-time flag for Webview, this disables all of Android, and the
+      // feature will be re-enabled for non-Webview Android by Finch.
+      base::FEATURE_DISABLED_BY_DEFAULT
+#else
+      base::FEATURE_ENABLED_BY_DEFAULT
+#endif
+};
 
 // Enable Display Locking JavaScript APIs.
 const base::Feature kDisplayLocking{"DisplayLocking",