Ensure all features are applied correctly.

When tests use a rule that enables features and the test enables yet
another feature separately only one set of features will end up getting
applied because the enable-feature/disable-feature flag is duplicated.
Ensure we aggregate all requests before applying.

BUG=786454

Change-Id: I79208e13f25de7c725d71f241481a454265d83c4
Reviewed-on: https://chromium-review.googlesource.com/830259Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Maria Khomenko <mariakhomenko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524517}

base/test/android/javatests/src/org/chromium/base/test/util/CommandLineFlags.java

@@ -5,6 +5,7 @@
 package org.chromium.base.test.util;
 
 import android.content.Context;
+import android.text.TextUtils;
 
 import org.junit.Assert;
 import org.junit.Rule;
@@ -22,6 +23,7 @@ import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -54,6 +56,8 @@ import java.util.Set;
  * Note that this class should never be instantiated.
  */
 public final class CommandLineFlags {
+    private static final String DISABLE_FEATURES = "disable-features";
+    private static final String ENABLE_FEATURES = "enable-features";
 
     /**
      * Adds command-line flags to the {@link org.chromium.base.CommandLine} for this test.
@@ -88,15 +92,33 @@ public final class CommandLineFlags {
         Assert.assertNotNull("Unable to get a non-null target context.", targetContext);
         CommandLine.reset();
         BaseChromiumApplication.initCommandLine(targetContext);
+        Set<String> enableFeatures = new HashSet<String>();
+        Set<String> disableFeatures = new HashSet<String>();
         Set<String> flags = getFlags(element);
         for (String flag : flags) {
             String[] parsedFlags = flag.split("=", 2);
             if (parsedFlags.length == 1) {
                 CommandLine.getInstance().appendSwitch(flag);
+            } else if (ENABLE_FEATURES.equals(parsedFlags[0])) {
+                // We collect enable/disable features flags separately and aggregate them because
+                // they may be specified multiple times, in which case the values will trample each
+                // other.
+                Collections.addAll(enableFeatures, parsedFlags[1].split(","));
+            } else if (DISABLE_FEATURES.equals(parsedFlags[0])) {
+                Collections.addAll(disableFeatures, parsedFlags[1].split(","));
             } else {
                 CommandLine.getInstance().appendSwitchWithValue(parsedFlags[0], parsedFlags[1]);
             }
         }
+
+        if (enableFeatures.size() > 0) {
+            CommandLine.getInstance().appendSwitchWithValue(
+                    ENABLE_FEATURES, TextUtils.join(",", enableFeatures));
+        }
+        if (disableFeatures.size() > 0) {
+            CommandLine.getInstance().appendSwitchWithValue(
+                    DISABLE_FEATURES, TextUtils.join(",", disableFeatures));
+        }
     }
 
     private static Set<String> getFlags(AnnotatedElement type) {