Enable InstanceID field trial by default

This makes it easier to write tests, since each test doesn't have to
enable the field trial (which is especially hard from Java).

Part of a series of patches:
1. https://codereview.chromium.org/1832833002 adds InstanceIDWithSubtype
2. https://codereview.chromium.org/1830983002 adds JNI bindings
3. https://codereview.chromium.org/1829023002 adds fake and test
4. https://codereview.chromium.org/1899753002 fixes strict mode violations
5. this patch
6. https://codereview.chromium.org/1923953002 adds crypto integration
7. https://codereview.chromium.org/1851423003 switches Push to InstanceIDs

BUG=589461, 477084

Review-Url: https://codereview.chromium.org/1854093002
Cr-Commit-Position: refs/heads/master@{#390339}

chrome/browser/extensions/api/instance_id/instance_id_apitest.cc

@@ -5,7 +5,6 @@
 #include <memory>
 #include <utility>
 
-#include "base/base_switches.h"
 #include "base/macros.h"
 #include "base/run_loop.h"
 #include "chrome/browser/extensions/api/instance_id/instance_id_api.h"
@@ -42,7 +41,6 @@ class InstanceIDApiTest : public ExtensionApiTest {
 
  protected:
   void SetUpOnMainThread() override;
-  void SetUpCommandLine(base::CommandLine* command_line) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InstanceIDApiTest);
@@ -58,14 +56,6 @@ void InstanceIDApiTest::SetUpOnMainThread() {
   ExtensionApiTest::SetUpOnMainThread();
 }
 
-void InstanceIDApiTest::SetUpCommandLine(base::CommandLine* command_line) {
-  ExtensionApiTest::SetUpCommandLine(command_line);
-
-  // Makes sure InstanceID is enabled for testing.
-  command_line->AppendSwitchASCII(
-       switches::kForceFieldTrials, "InstanceID/Enabled/");
-}
-
 IN_PROC_BROWSER_TEST_F(InstanceIDApiTest, GetID) {
   ASSERT_TRUE(RunExtensionTest("instance_id/get_id"));
 }

components/gcm_driver/gcm_driver_desktop_unittest.cc

@@ -11,7 +11,6 @@
 #include "base/files/scoped_temp_dir.h"
 #include "base/location.h"
 #include "base/macros.h"
-#include "base/metrics/field_trial.h"
 #include "base/run_loop.h"
 #include "base/strings/string_util.h"
 #include "base/test/test_simple_task_runner.h"
@@ -167,7 +166,6 @@ class GCMDriverTest : public testing::Test {
   TestingPrefServiceSimple prefs_;
   base::MessageLoopForUI message_loop_;
   base::Thread io_thread_;
-  base::FieldTrialList field_trial_list_;
   std::unique_ptr<GCMDriverDesktop> driver_;
   std::unique_ptr<FakeGCMAppHandler> gcm_app_handler_;
   std::unique_ptr<FakeGCMConnectionObserver> gcm_connection_observer_;
@@ -187,7 +185,6 @@ class GCMDriverTest : public testing::Test {
 
 GCMDriverTest::GCMDriverTest()
     : io_thread_("IOThread"),
-      field_trial_list_(NULL),
       registration_result_(GCMClient::UNKNOWN_ERROR),
       send_result_(GCMClient::UNKNOWN_ERROR),
       unregistration_result_(GCMClient::UNKNOWN_ERROR) {
@@ -950,9 +947,6 @@ void GCMChannelStatusSyncerTest::SetUp() {
   GCMDriverTest::SetUp();
 
   url_fetcher_factory_.set_remove_fetcher_on_delete(true);
-
-  // Turn on all-user support.
-  ASSERT_TRUE(base::FieldTrialList::CreateFieldTrial("GCM", "Enabled"));
 }
 
 void GCMChannelStatusSyncerTest::CompleteGCMChannelStatusRequest(

components/gcm_driver/instance_id/instance_id_driver.cc

@@ -5,6 +5,7 @@
 #include "components/gcm_driver/instance_id/instance_id_driver.h"
 
 #include "base/metrics/field_trial.h"
+#include "base/strings/string_util.h"
 #include "build/build_config.h"
 #include "components/gcm_driver/gcm_driver.h"
 #include "components/gcm_driver/instance_id/instance_id.h"
@@ -13,14 +14,15 @@ namespace instance_id {
 
 namespace {
 const char kInstanceIDFieldTrialName[] = "InstanceID";
-const char kInstanceIDFieldTrialEnabledGroupName[] = "Enabled";
+const char kInstanceIDFieldTrialDisabledGroupPrefix[] = "Disabled";
 }  // namespace
 
 // static
 bool InstanceIDDriver::IsInstanceIDEnabled() {
   std::string group_name =
       base::FieldTrialList::FindFullName(kInstanceIDFieldTrialName);
-  return group_name == kInstanceIDFieldTrialEnabledGroupName;
+  return !base::StartsWith(group_name, kInstanceIDFieldTrialDisabledGroupPrefix,
+                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
 InstanceIDDriver::InstanceIDDriver(gcm::GCMDriver* gcm_driver)