Expose FCMInvalidations to Java

We've observed some tests CHECK-failing with:
[FATAL:chrome_feature_list.cc(185)] Check failed: false. Queried feature cannot be found in ChromeFeatureList: FCMInvalidations

Since we have plans to expose this feature to Java anyway, let's keep
existing tests happy by exposing the feature to Java.

Bug: 879246
Change-Id: Ie148a8d31a5d93a700a569090f7c4a6b3d27194b
Reviewed-on: https://chromium-review.googlesource.com/c/1296592Reviewed-by: Tatiana Gornak <melandory@chromium.org>
Reviewed-by: Pavel Yatsuk <pavely@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602003}

chrome/browser/BUILD.gn

@@ -2540,6 +2540,7 @@ jumbo_split_static_library("browser") {
       "//components/embedder_support/android:web_contents_delegate",
       "//components/feed:buildflags",
       "//components/feed:feature_list",
+      "//components/invalidation/impl:feature_list",
       "//components/language/android:language_bridge",
       "//components/payments/content/android",
       "//components/resources:components_resources",

chrome/browser/android/chrome_feature_list.cc

@@ -16,6 +16,7 @@
 #include "components/autofill/core/common/autofill_features.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_features.h"
 #include "components/feed/feed_feature_list.h"
+#include "components/invalidation/impl/invalidation_switches.h"
 #include "components/language/core/common/language_experiments.h"
 #include "components/ntp_snippets/contextual/contextual_suggestions_features.h"
 #include "components/ntp_snippets/features.h"
@@ -73,6 +74,7 @@ const base::Feature* kFeaturesExposedToJava[] = {
     &features::kWebAuth,
     &features::kWebPayments,
     &feed::kInterestFeedContentSuggestions,
+    &invalidation::switches::kFCMInvalidations,
     &kAdjustWebApkInstallationSpace,
     &kAndroidPayIntegrationV1,
     &kAndroidPayIntegrationV2,

components/invalidation/impl/BUILD.gn

@@ -6,6 +6,17 @@ if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
+static_library("feature_list") {
+  sources = [
+    "invalidation_switches.cc",
+    "invalidation_switches.h",
+  ]
+
+  deps = [
+    "//base",
+  ]
+}
+
 static_library("impl") {
   sources = [
     "deprecated_invalidator_registrar.cc",
@@ -19,8 +30,6 @@ static_library("impl") {
     "invalidation_service_util.h",
     "invalidation_state_tracker.cc",
     "invalidation_state_tracker.h",
-    "invalidation_switches.cc",
-    "invalidation_switches.h",
     "invalidator.cc",
     "invalidator.h",
     "invalidator_registrar.cc",
@@ -46,6 +55,7 @@ static_library("impl") {
   ]
 
   public_deps = [
+    ":feature_list",
     "//components/invalidation/public",
   ]
   deps = [