Allow controlling the Instant field trial through a command line flag.

This also allows us to disable the field trial for all tests, without
hacking around the kInstantEnabledOnce preference.

BUG=none
TEST=none


Review URL: http://codereview.chromium.org/8198027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@104794 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 23 insertions, 7 deletions

diff --git a/chrome/browser/instant/instant_field_trial.cc b/chrome/browser/instant/instant_field_trial.cc
index dc68ac9..13a0b42 100644
--- a/chrome/browser/instant/instant_field_trial.cc
+++ b/chrome/browser/instant/instant_field_trial.cc
@@ -4,10 +4,12 @@
 
 #include "chrome/browser/instant/instant_field_trial.h"
 
+#include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "chrome/browser/metrics/metrics_service.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
 
 namespace {
@@ -39,6 +41,16 @@ void InstantFieldTrial::Activate() {
 
 // static
 InstantFieldTrial::Group InstantFieldTrial::GetGroup(Profile* profile) {
+  CommandLine* command_line = CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kInstantFieldTrial)) {
+    std::string switch_value =
+        command_line->GetSwitchValueASCII(switches::kInstantFieldTrial);
+    if (switch_value == switches::kInstantFieldTrialInstant)
+      return EXPERIMENT1;
+    else
+      return INACTIVE;
+  }
+
   if (!profile || profile->IsOffTheRecord())
     return INACTIVE;
 
diff --git a/chrome/browser/metrics/metrics_service_uitest.cc b/chrome/browser/metrics/metrics_service_uitest.cc
index f323fdc..20fca2b 100644
--- a/chrome/browser/metrics/metrics_service_uitest.cc
+++ b/chrome/browser/metrics/metrics_service_uitest.cc
@@ -39,11 +39,6 @@ class MetricsServiceTest : public UITest {
     scoped_refptr<BrowserProxy> window = automation()->GetBrowserWindow(0);
     ASSERT_TRUE(window.get());
 
-    // The Instant field trial causes a preload of the default search engine,
-    // which messes up the expected page load count. Setting this preference
-    // disables the field trial.
-    ASSERT_TRUE(window->SetBooleanPreference(prefs::kInstantEnabledOnce, true));
-
     FilePath page1_path;
     ASSERT_TRUE(PathService::Get(chrome::DIR_TEST_DATA, &page1_path));
     page1_path = page1_path.AppendASCII("title2.html");
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index aa617a0..14f5394 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -669,6 +669,12 @@ const char kImportFromFile[]                = "import-from-file";
 // Causes the browser to launch directly in incognito mode.
 const char kIncognito[]                     = "incognito";
 
+// Control the Instant field trial. Valid values are defined below. If an
+// unknown value is supplied on the command line, the field trial is disabled.
+const char kInstantFieldTrial[]             = "instant-field-trial";
+// The field trial is forced into the INSTANT_EXPERIMENT group.
+const char kInstantFieldTrialInstant[]      = "instant";
+
 // URL to use for instant. If specified this overrides the url from the
 // TemplateURL.
 const char kInstantURL[]                    = "instant-url";
diff --git a/chrome/common/chrome_switches.h b/chrome/common/chrome_switches.h
index 5b54d39..872136d 100644
--- a/chrome/common/chrome_switches.h
+++ b/chrome/common/chrome_switches.h
@@ -187,6 +187,8 @@ extern const char kHstsHosts[];
 extern const char kImport[];
 extern const char kImportFromFile[];
 extern const char kIncognito[];
+extern const char kInstantFieldTrial[];
+extern const char kInstantFieldTrialInstant[];
 extern const char kInstantURL[];
 extern const char kKeepAliveForTest[];
 extern const char kLoadExtension[];
diff --git a/chrome/test/base/test_launcher_utils.cc b/chrome/test/base/test_launcher_utils.cc
index 4dfe1f7..d8239eb 100644
--- a/chrome/test/base/test_launcher_utils.cc
+++ b/chrome/test/base/test_launcher_utils.cc
@@ -53,6 +53,9 @@ void PrepareBrowserCommandLineForTests(CommandLine* command_line) {
   // See crbug.com/89808.
   // command_line->AppendSwitch(switches::kUseMockKeychain);
 #endif
+
+  // Disable the Instant field trial, which may cause unexpected page loads.
+  command_line->AppendSwitchASCII(switches::kInstantFieldTrial, "disabled");
 }
 
 bool OverrideUserDataDir(const FilePath& user_data_dir) {
diff --git a/chrome/test/functional/instant.py b/chrome/test/functional/instant.py
index 796b687..917b10f 100644
--- a/chrome/test/functional/instant.py
+++ b/chrome/test/functional/instant.py
@@ -21,7 +21,6 @@ class InstantSettingsTest(pyauto.PyUITest):
                      msg='Instant is enabled by default.')
     # Enable instant.
     self.SetPrefs(pyauto.kInstantEnabled, True)
-    self.SetPrefs(pyauto.kInstantEnabledOnce, True)
     self.assertTrue(self.GetPrefsInfo().Prefs(pyauto.kInstantEnabled),
                     msg='Instant is not enabled.')
     self.SetOmniboxText('google.com')
@@ -42,7 +41,6 @@ class InstantTest(pyauto.PyUITest):
   def setUp(self):
     pyauto.PyUITest.setUp(self)
     self.SetPrefs(pyauto.kInstantEnabled, True)
-    self.SetPrefs(pyauto.kInstantEnabledOnce, True)
 
   def _DoneLoading(self):
     info = self.GetInstantInfo()