Update from https://crrev.com/303153

base/metrics/field_trial_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/metrics/field_trial.h"
 
 #include "base/build_time.h"
 #include "base/message_loop/message_loop.h"
 #include "base/rand_util.h"
 #include "base/run_loop.h"
@@ skipping 410 matching lines @@
 TEST_F(FieldTrialTest, BogusRestore) {
   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
       "MissingSlash", FieldTrialList::DONT_ACTIVATE_TRIALS,
       std::set<std::string>()));
   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
       "MissingGroupName/", FieldTrialList::DONT_ACTIVATE_TRIALS,
       std::set<std::string>()));
   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
       "noname, only group/", FieldTrialList::DONT_ACTIVATE_TRIALS,
       std::set<std::string>()));
+  EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
+      "/emptyname", FieldTrialList::DONT_ACTIVATE_TRIALS,
+      std::set<std::string>()));
+  EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
+      "*/emptyname", FieldTrialList::DONT_ACTIVATE_TRIALS,
+      std::set<std::string>()));
 }
 
 TEST_F(FieldTrialTest, DuplicateRestore) {
   scoped_refptr<FieldTrial> trial =
       CreateFieldTrial("Some name", 10, "Default", NULL);
   trial->AppendGroup("Winner", 10);
   // Finalize the group selection by accessing the selected group.
   trial->group();
   std::string save_string;
   FieldTrialList::StatesToString(&save_string);
@@ skipping 42 matching lines @@
   EXPECT_EQ("zyx", FieldTrialList::FindFullName("Xyz"));
 
   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
   ASSERT_EQ(2U, active_groups.size());
   EXPECT_EQ("Abc", active_groups[0].trial_name);
   EXPECT_EQ("def", active_groups[0].group_name);
   EXPECT_EQ("Xyz", active_groups[1].trial_name);
   EXPECT_EQ("zyx", active_groups[1].group_name);
 }
 
+TEST_F(FieldTrialTest, CreateTrialsFromStringForceActivation) {
+  ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
+  ASSERT_FALSE(FieldTrialList::TrialExists("def"));
+  ASSERT_FALSE(FieldTrialList::TrialExists("Xyz"));
+  ASSERT_TRUE(FieldTrialList::CreateTrialsFromString(
+      "*Abc/cba/def/fed/*Xyz/zyx/", FieldTrialList::DONT_ACTIVATE_TRIALS,
+      std::set<std::string>()));
+
+  FieldTrial::ActiveGroups active_groups;
+  FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
+  ASSERT_EQ(2U, active_groups.size());
+  EXPECT_EQ("Abc", active_groups[0].trial_name);
+  EXPECT_EQ("cba", active_groups[0].group_name);
+  EXPECT_EQ("Xyz", active_groups[1].trial_name);
+  EXPECT_EQ("zyx", active_groups[1].group_name);
+}
+
 TEST_F(FieldTrialTest, CreateTrialsFromStringActiveObserver) {
   ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
 
   TestFieldTrialObserver observer;
   ASSERT_TRUE(FieldTrialList::CreateTrialsFromString(
       "Abc/def/", FieldTrialList::ACTIVATE_TRIALS, std::set<std::string>()));
 
   RunLoop().RunUntilIdle();
   EXPECT_EQ("Abc", observer.trial_name());
   EXPECT_EQ("def", observer.group_name());
@@ skipping 493 matching lines @@
   // Trying to instantiate a one-time randomized field trial before the
   // FieldTrialList is created should crash.
   EXPECT_DEATH(FieldTrialList::FactoryGetFieldTrial(
       "OneTimeRandomizedTrialWithoutFieldTrialList", 100, kDefaultGroupName,
       base::FieldTrialList::kNoExpirationYear, 1, 1,
       base::FieldTrial::ONE_TIME_RANDOMIZED, NULL), "");
 }
 #endif
 
 }  // namespace base