[supportlib] Support a :dev feature suffix.

:dev suffixed features will only be available if the device is
userdebug. This makes it possible to develop support library changes in
multiple steps, and then expose the feature with a final CL that removes
the suffix, without running the risk that applications will
inadvertently release code depending on the behaviour of an in-progress
implementation of a feature.

Bug: 908648
Change-Id: Iae98386992eb113356cf74be3eda125af10d867a
Reviewed-on: https://chromium-review.googlesource.com/c/1349327
Commit-Queue: Tobias Sargeant <tobiasjs@chromium.org>
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611061}

android_webview/support_library/boundary_interfaces/src/org/chromium/support_lib_boundary/util/BoundaryInterfaceReflectionUtil.java

@@ -10,6 +10,8 @@ import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
+import java.util.Arrays;
+import java.util.Collection;
 
 /**
  * A set of utility methods used for calling across the support library boundary.
@@ -129,14 +131,21 @@ public class BoundaryInterfaceReflectionUtil {
         }
     }
 
+    private static boolean isDebuggable() {
+        return !Build.TYPE.equals("user");
+    }
+
     /**
      * Check whether a set of features {@param features} contains a certain feature {@param
      * soughtFeature}.
      */
+    public static boolean containsFeature(Collection<String> features, String soughtFeature) {
+        assert !soughtFeature.endsWith(Features.DEV_SUFFIX);
+        return features.contains(soughtFeature)
+                || (isDebuggable() && features.contains(soughtFeature + Features.DEV_SUFFIX));
+    }
+
     public static boolean containsFeature(String[] features, String soughtFeature) {
-        for (String feature : features) {
-            if (feature.equals(soughtFeature)) return true;
-        }
-        return false;
+        return containsFeature(Arrays.asList(features), soughtFeature);
     }
 }

android_webview/support_library/boundary_interfaces/src/org/chromium/support_lib_boundary/util/Features.java

@@ -10,6 +10,9 @@ package org.chromium.support_lib_boundary.util;
  * Chromium can share its definition.
  */
 public class Features {
+    // Features suffixed with DEV will only be visible on debug devices.
+    public static final String DEV_SUFFIX = ":dev";
+
     // This class just contains constants representing features.
     private Features() {}