Disable ARCore in official builds

Different channel builds on Android must have identical .so files. Previously
ARCore was only enabled on the default channel but disabled on Canary, Dev,
Beta, and Stable, which broke channel builds. Replacing the channel check with
an official build check is the closest approximation that avoids reverting
https://crrev.com/559923 completely.

TBR: mthiesse@chromium.org
Bug: 845080
Change-Id: Id75d793827db0a489523f1fe3ced094b0821d35d
Reviewed-on: https://chromium-review.googlesource.com/1065917
Commit-Queue: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Ian Vollick <vollick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560263}

device/vr/buildflags/buildflags.gni

@@ -33,14 +33,16 @@ declare_args() {
 
   # TODO(crbug.com/837999, crbug.com/841389): We currently only support arm and
   # we are limiting to canary and dev until binary size issues are resolved.
-  # TODO(crbug.com/841881): add android_channel == "dev" || "canary".
-  enable_arcore = is_android && !is_chromecast && current_cpu == "arm" &&
-                  android_channel == "default"
+  # TODO(crbug.com/841881, crbug.com/845080): add android_channel == "dev"
+  # || "canary" || "default".
+  enable_arcore =
+      is_android && !is_chromecast && current_cpu == "arm" && !is_official_build
 
   # TODO(crbug.com/841389): This should not be necessary once 64 bit is properly
   # supported and enable_arcore permits arm64 as well.
-  # TODO(crbug.com/841881): add android_channel == "dev" || "canary".
-  enable_arcore_java = is_android && !is_chromecast &&
-                       (current_cpu == "arm" || current_cpu == "arm64") &&
-                       android_channel == "default"
+  # TODO(crbug.com/841881, crbug.com/845080): add android_channel == "dev"
+  # || "canary" || "default".
+  enable_arcore_java =
+      is_android && !is_chromecast &&
+      (current_cpu == "arm" || current_cpu == "arm64") && !is_official_build
 }