[KeyboardLock] Removing KeyboardLock blink feature

Now that we've branched to M69 and the KeyboardLock feature is enabled
by default, we can remove the blink API feature flag.

Note: I want to keep the Chrome feature flags around a bit longer, but
will be removing them at some point in the future.

BUG=680809

Change-Id: I6dcb76a0a8e7874fd20627f9126ff48a9a0625a6
Reviewed-on: https://chromium-review.googlesource.com/1073674Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Commit-Queue: Joe Downing <joedow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563099}

content/child/runtime_features.cc

@@ -400,9 +400,6 @@ void SetRuntimeFeaturesDefaultsAndUpdateFromArgs(
       "FeaturePolicyForPermissions",
       base::FeatureList::IsEnabled(features::kUseFeaturePolicyForPermissions));
 
-  if (base::FeatureList::IsEnabled(features::kKeyboardLockAPI))
-    WebRuntimeFeatures::EnableFeatureFromString("KeyboardLock", true);
-
   if (base::FeatureList::IsEnabled(features::kLazyFrameLoading))
     WebRuntimeFeatures::EnableLazyFrameLoading(true);
   if (base::FeatureList::IsEnabled(features::kLazyFrameVisibleLoadTimeMetrics))

third_party/blink/renderer/modules/keyboard/keyboard.idl

@@ -2,10 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// TODO(joedow): Remove RuntimeEnabled flag after the next branch point.
 [
     Exposed=Window,
-    RuntimeEnabled=KeyboardLock,
     SecureContext
 ] interface Keyboard {
     // Keyboard Lock specification: https://w3c.github.io/keyboard-lock/

third_party/blink/renderer/modules/keyboard/navigator_keyboard.idl

@@ -3,8 +3,7 @@
 // found in the LICENSE file.
 
 [
-    ImplementedAs=NavigatorKeyboard,
-    RuntimeEnabled=KeyboardLock
+    ImplementedAs=NavigatorKeyboard
 ] partial interface Navigator {
     [SameObject, SecureContext] readonly attribute Keyboard keyboard;
 };

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -625,10 +625,6 @@
       name: "JSImageDecode",
       status: "stable",
     },
-    {
-      name: "KeyboardLock",
-      status: "stable",
-    },
     {
       name: "KeyboardMap",
       status: "experimental",