Handful of related instant changes:

chrome/browser/instant/instant_controller.cc

Index: chrome/browser/instant/instant_controller.cc
diff --git a/chrome/browser/instant/instant_controller.cc b/chrome/browser/instant/instant_controller.cc
index 151308c538ab07c28988c54d03ed55faabfb22a7..eb10fb00374978bab25567c288232ada7c7edadb 100644
--- a/chrome/browser/instant/instant_controller.cc
+++ b/chrome/browser/instant/instant_controller.cc
@@ -5,10 +5,13 @@
 #include "chrome/browser/instant/instant_controller.h"
 
 #include "base/command_line.h"
+#include "base/metrics/histogram.h"
+#include "base/rand_util.h"
 #include "chrome/browser/autocomplete/autocomplete_match.h"
 #include "chrome/browser/instant/instant_delegate.h"
 #include "chrome/browser/instant/instant_loader.h"
 #include "chrome/browser/instant/instant_loader_manager.h"
+#include "chrome/browser/instant/promo_counter.h"
 #include "chrome/browser/platform_util.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profile.h"
@@ -24,10 +27,61 @@
 // Number of ms to delay between loading urls.
 static const int kUpdateDelayMS = 200;
 
+static InstantController::Type GetType(Profile* profile) {
+  return InstantController::IsEnabled(profile,
+                                      InstantController::PREDICTIVE_TYPE) ?
+      InstantController::PREDICTIVE_TYPE : InstantController::VERBATIM_TYPE;
+}
+
+InstantController::InstantController(Profile* profile,
+                                     InstantDelegate* delegate)
+    : delegate_(delegate),
+      tab_contents_(NULL),
+      is_active_(false),
+      commit_on_mouse_up_(false),
+      last_transition_type_(PageTransition::LINK),
+      type_(GetType(profile)) {
+  PrefService* service = profile->GetPrefs();
+  if (service) {
+    // kInstantWasEnabledOnce was added after instant, set it now to make sure

[Evan Stade, 2010/11/15 19:59:23]

nit: kInstantEnabledOnce

+    // it is correctly set.
+    service->SetBoolean(prefs::kInstantEnabledOnce, true);
+  }
+}
+
+InstantController::~InstantController() {
+}
+
 // static
 void InstantController::RegisterUserPrefs(PrefService* prefs) {
   prefs->RegisterBooleanPref(prefs::kInstantConfirmDialogShown, false);
   prefs->RegisterBooleanPref(prefs::kInstantEnabled, false);
+  prefs->RegisterBooleanPref(prefs::kInstantEnabledOnce, false);
+  prefs->RegisterInt64Pref(prefs::kInstantEnabledTime, false);
+  prefs->RegisterIntegerPref(prefs::kInstantType, 0);
+  PromoCounter::RegisterUserPrefs(prefs, prefs::kInstantPromo);
+}
+
+// static
+void InstantController::RecordMetrics(Profile* profile) {
+  if (!IsEnabled(profile))
+    return;
+
+  PrefService* service = profile->GetPrefs();
+  if (service) {
+    int64 enable_time = service->GetInt64(prefs::kInstantEnabledTime);
+    if (!enable_time) {
+      service->SetInt64(prefs::kInstantEnabledTime,
+                        base::Time::Now().ToInternalValue());
+    } else {
+      base::TimeDelta delta =
+          base::Time::Now() - base::Time::FromInternalValue(enable_time);
+      std::string name = IsEnabled(profile, PREDICTIVE_TYPE) ?
+          "Instant.EnabledTime.Predictive" : "Instant.EnabledTime.Verbatim";
+      // Histogram from 1 hour to 30 days.
+      UMA_HISTOGRAM_CUSTOM_COUNTS(name, delta.InHours(), 1, 30 * 24, 50);

[Evan Stade, 2010/11/15 19:59:23]

so the idea is we're tracking how long people leave it enabled?

[sky, 2010/11/15 20:15:26]

Yes.

+    }
+  }
 }
 
 // static
@@ -38,34 +92,70 @@ bool InstantController::IsEnabled(Profile* profile) {
 
 // static
 bool InstantController::IsEnabled(Profile* profile, Type type) {
+  // CommandLine takes precedence.
   CommandLine* cl = CommandLine::ForCurrentProcess();
-  if (type == PREDICTIVE_TYPE) {
-    return (cl->HasSwitch(switches::kEnablePredictiveInstant) ||
-            (profile->GetPrefs() &&
-             profile->GetPrefs()->GetBoolean(prefs::kInstantEnabled)));
+  if (type == PREDICTIVE_TYPE &&
+      cl->HasSwitch(switches::kEnablePredictiveInstant)) {
+    return true;
+  }
+  if (type == VERBATIM_TYPE &&
+      cl->HasSwitch(switches::kEnableVerbatimInstant)) {
+    return true;
   }
-  return cl->HasSwitch(switches::kEnableVerbatimInstant);
-}
 
-static InstantController::Type GetType(Profile* profile) {
-  return InstantController::IsEnabled(profile,
-                                      InstantController::PREDICTIVE_TYPE) ?
-      InstantController::PREDICTIVE_TYPE : InstantController::VERBATIM_TYPE;
+  // Then prefs.
+  PrefService* prefs = profile->GetPrefs();
+  if (!prefs->GetBoolean(prefs::kInstantEnabled))
+    return false;
+
+  Type pref_type = prefs->GetInteger(prefs::kInstantType) ==
+      static_cast<int>(PREDICTIVE_TYPE) ? PREDICTIVE_TYPE : VERBATIM_TYPE;
+  return pref_type == type;
 }
 
-InstantController::InstantController(Profile* profile,
-                                     InstantDelegate* delegate)
-    : delegate_(delegate),
-      tab_contents_(NULL),
-      is_active_(false),
-      commit_on_mouse_up_(false),
-      last_transition_type_(PageTransition::LINK),
-      type_(GetType(profile)) {
+// static
+void InstantController::Enable(Profile* profile) {
+  PromoCounter* promo_counter = profile->GetInstantPromoCounter();
+  if (promo_counter)
+    promo_counter->Hide();
+
+  PrefService* service = profile->GetPrefs();
+  if (!service)
+    return;
+
+  service->SetBoolean(prefs::kInstantEnabled, true);
+  service->SetBoolean(prefs::kInstantConfirmDialogShown, true);
+  service->SetInt64(prefs::kInstantEnabledTime,
+                    base::Time::Now().ToInternalValue());
+  service->SetBoolean(prefs::kInstantEnabledOnce, true);
+  // Randomly pick a type. We're doing this to get feedback as to which variant
+  // folks prefer.
+  service->SetInteger(prefs::kInstantType,
+                      base::RandInt(static_cast<int>(PREDICTIVE_TYPE),
+                                    static_cast<int>(LAST_TYPE)));
 }
 
-InstantController::~InstantController() {
+// static
+void InstantController::Disable(Profile* profile) {
+  PrefService* service = profile->GetPrefs();
+  if (!service)
+    return;
+
+  service->SetBoolean(prefs::kInstantEnabled, false);
+
+  int64 enable_time = service->GetInt64(prefs::kInstantEnabledTime);
+  if (!enable_time)
+    return;
+
+  base::TimeDelta delta =
+      base::Time::Now() - base::Time::FromInternalValue(enable_time);
+  std::string name = IsEnabled(profile, PREDICTIVE_TYPE) ?
+      "Instant.TimeToDisable.Predictive" : "Instant.TimeToDisable.Verbatim";
+  // histogram from 1 minute to 10 days.
+  UMA_HISTOGRAM_CUSTOM_COUNTS(name, delta.InMinutes(), 1, 60 * 24 * 10, 50);
 }
 
+
 void InstantController::Update(TabContents* tab_contents,
                                const AutocompleteMatch& match,
                                const string16& user_text,