Lo-Fi implicit opt out

If a user requests 'Show images' for k pages in a session,
disable LoFi for the remainder of that session.

If LoFi is disabled for j consecutive sessions, disable
LoFi "permanently". Where "permanently" is used loosely
such that we could silently turn it back on using the
implicit_opt_out_version number.

BUG=485619

Review URL: https://codereview.chromium.org/1148683009

Cr-Commit-Position: refs/heads/master@{#333869}

14 files changed, 271 insertions, 0 deletions

diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc
index aab7569..dd55a9e 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.cc
@@ -752,6 +752,11 @@ void DataReductionProxyConfig::SecureProxyCheck(
                                                      fetcher_callback);
 }
 
+void DataReductionProxyConfig::SetLoFiModeOff() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  lofi_status_ = LOFI_STATUS_OFF;
+}
+
 void DataReductionProxyConfig::UpdateLoFiStatusOnMainFrameRequest(
     bool user_temporarily_disabled_lofi,
     const net::NetworkQualityEstimator* network_quality_estimator) {
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h
index b015f06..3c85e41 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_config.h
@@ -234,6 +234,9 @@ class DataReductionProxyConfig
   // Should be called on all URL requests (main frame and non main frame).
   bool ShouldUseLoFiHeaderForRequests() const;
 
+  // Sets |lofi_status_| to LOFI_STATUS_OFF.
+  void SetLoFiModeOff();
+
   // Updates |lofi_status_| based on the arguments provided and the current
   // value of |lofi_status_|.
   // |network_quality_estimator| may be NULL.
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.cc
index 0c21098..f9b68cc 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.cc
@@ -265,6 +265,10 @@ void DataReductionProxyIOData::SetDataReductionProxyConfiguration(
     config_client_->ApplySerializedConfig(serialized_config);
 }
 
+void DataReductionProxyIOData::SetLoFiModeOff() {
+  config_->SetLoFiModeOff();
+}
+
 void DataReductionProxyIOData::UpdateContentLengths(
     int64 received_content_length,
     int64 original_content_length,
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h
index d63529f..6bfdee8 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_io_data.h
@@ -88,6 +88,9 @@ class DataReductionProxyIOData : public DataReductionProxyEventStorageDelegate {
   // Applies a serialized Data Reduction Proxy configuration.
   void SetDataReductionProxyConfiguration(const std::string& serialized_config);
 
+  // Sets Lo-Fi mode off in |config_|.
+  void SetLoFiModeOff();
+
   // Bridge methods to safely call to the UI thread objects.
   void UpdateContentLengths(int64 received_content_length,
                             int64 original_content_length,
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_prefs.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_prefs.cc
index 5c2acf2..33d13a880 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_prefs.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_prefs.cc
@@ -59,6 +59,9 @@ void RegisterSyncableProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
       prefs::kDailyOriginalContentLengthViaDataReductionProxy);
   registry->RegisterListPref(prefs::kDailyContentLengthViaDataReductionProxy);
   registry->RegisterInt64Pref(prefs::kDailyHttpContentLengthLastUpdateDate, 0L);
+  registry->RegisterIntegerPref(prefs::kLoFiImplicitOptOutVersion, 0);
+  registry->RegisterIntegerPref(prefs::kLoFiLoadImagesPerSession, 0);
+  registry->RegisterIntegerPref(prefs::kLoFiConsecutiveSessionDisables, 0);
   registry->RegisterInt64Pref(prefs::kSimulatedConfigRetrieveTime, 0L);
   registry->RegisterStringPref(prefs::kDataReductionProxyConfig, std::string());
 }
@@ -107,6 +110,9 @@ void RegisterPrefs(PrefRegistrySimple* registry) {
       prefs::kDailyContentLengthViaDataReductionProxy);
   registry->RegisterInt64Pref(
       prefs::kDailyHttpContentLengthLastUpdateDate, 0L);
+  registry->RegisterIntegerPref(prefs::kLoFiImplicitOptOutVersion, 0);
+  registry->RegisterIntegerPref(prefs::kLoFiLoadImagesPerSession, 0);
+  registry->RegisterIntegerPref(prefs::kLoFiConsecutiveSessionDisables, 0);
   registry->RegisterInt64Pref(prefs::kSimulatedConfigRetrieveTime, 0L);
   registry->RegisterStringPref(prefs::kDataReductionProxyConfig, std::string());
 }
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_service.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_service.cc
index 8490a55..3b47836 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_service.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_service.cc
@@ -13,6 +13,7 @@
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_service_observer.h"
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_event_store.h"
+#include "components/data_reduction_proxy/core/common/data_reduction_proxy_params.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.h"
 
 namespace data_reduction_proxy {
@@ -57,6 +58,8 @@ void DataReductionProxyService::SetIOData(
               io_data_, config_value));
     }
   }
+
+  InitializeLoFiPrefs();
 }
 
 void DataReductionProxyService::Shutdown() {
@@ -125,6 +128,59 @@ void DataReductionProxyService::SetLoFiModeActiveOnMainFrame(
   settings_->SetLoFiModeActiveOnMainFrame(lo_fi_mode_active);
 }
 
+void DataReductionProxyService::SetLoFiModeOff() {
+  DCHECK(CalledOnValidThread());
+  if (io_task_runner_->BelongsToCurrentThread()) {
+    io_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&DataReductionProxyIOData::SetLoFiModeOff, io_data_));
+    return;
+  }
+  io_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&DataReductionProxyIOData::SetLoFiModeOff, io_data_));
+}
+
+void DataReductionProxyService::InitializeLoFiPrefs() {
+  DCHECK(CalledOnValidThread());
+  if (prefs_) {
+    int lo_fi_user_requests_for_images_per_session =
+        DataReductionProxyParams::GetFieldTrialParameterAsInteger(
+            DataReductionProxyParams::GetLoFiFieldTrialName(),
+            "load_images_requests_per_session", 3);
+
+    int lo_fi_implicit_opt_out_version =
+        DataReductionProxyParams::GetFieldTrialParameterAsInteger(
+            DataReductionProxyParams::GetLoFiFieldTrialName(),
+            "implicit_opt_out_version", 0);
+
+    int lo_fi_consecutive_session_disables =
+        DataReductionProxyParams::GetFieldTrialParameterAsInteger(
+            DataReductionProxyParams::GetLoFiFieldTrialName(),
+            "consecutive_session_disables", 3);
+
+    if (prefs_->GetInteger(prefs::kLoFiImplicitOptOutVersion) <
+        lo_fi_implicit_opt_out_version) {
+      // We have a new implicit opt out version, reset the consecutive session
+      // disables count so that Lo-Fi can be enabled again.
+      prefs_->SetInteger(prefs::kLoFiConsecutiveSessionDisables, 0);
+      prefs_->SetInteger(prefs::kLoFiImplicitOptOutVersion,
+                         lo_fi_implicit_opt_out_version);
+    } else if (prefs_->GetInteger(prefs::kLoFiConsecutiveSessionDisables) >=
+               lo_fi_consecutive_session_disables) {
+      SetLoFiModeOff();
+    } else if (prefs_->GetInteger(prefs::kLoFiLoadImagesPerSession) <
+               lo_fi_user_requests_for_images_per_session) {
+      // If the last session didn't have
+      // |lo_fi_user_requests_for_images_per_session| and the number of
+      // |consecutive_session_disables| hasn't been met, reset the consecutive
+      // sessions count.
+      prefs_->SetInteger(prefs::kLoFiConsecutiveSessionDisables, 0);
+    }
+    prefs_->SetInteger(prefs::kLoFiLoadImagesPerSession, 0);
+  }
+}
+
 void DataReductionProxyService::SetInt64Pref(const std::string& pref_path,
                                              int64 value) {
   if (prefs_)
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_service.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_service.h
index 9ef540e..b4eff3b 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_service.h
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_service.h
@@ -5,6 +5,8 @@
 #ifndef COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_SERVICE_H_
 #define COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_REDUCTION_PROXY_SERVICE_H_
 
+#include <string>
+
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
@@ -95,6 +97,12 @@ class DataReductionProxyService
   // DataReductionProxySettings.
   void SetLoFiModeActiveOnMainFrame(bool lo_fi_mode_active);
 
+  // Sets Lo-Fi mode off on the IO thread.
+  void SetLoFiModeOff();
+
+  // Initializes the Lo-Fi implicit opt out prefs.
+  void InitializeLoFiPrefs();
+
   // Stores an int64 value in |prefs_|.
   void SetInt64Pref(const std::string& pref_path, int64 value);
 
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.cc
index a53b660..8866869 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.cc
@@ -40,6 +40,10 @@ DataReductionProxySettings::DataReductionProxySettings()
       lo_fi_show_image_requested_(false),
       prefs_(NULL),
       config_(nullptr) {
+  lo_fi_user_requests_for_images_per_session_ =
+      DataReductionProxyParams::GetFieldTrialParameterAsInteger(
+          DataReductionProxyParams::GetLoFiFieldTrialName(),
+          "load_images_requests_per_session", 3);
 }
 
 DataReductionProxySettings::~DataReductionProxySettings() {
@@ -191,6 +195,20 @@ void DataReductionProxySettings::SetLoFiShowImageRequested() {
   lo_fi_show_image_requested_ = true;
 }
 
+void DataReductionProxySettings::IncrementLoFiUserRequestsForImages() {
+  if (!prefs_)
+    return;
+  prefs_->SetInteger(prefs::kLoFiLoadImagesPerSession,
+                     prefs_->GetInteger(prefs::kLoFiLoadImagesPerSession) + 1);
+  if (prefs_->GetInteger(prefs::kLoFiLoadImagesPerSession) >=
+      lo_fi_user_requests_for_images_per_session_) {
+    data_reduction_proxy_service_->SetLoFiModeOff();
+    prefs_->SetInteger(
+        prefs::kLoFiConsecutiveSessionDisables,
+        prefs_->GetInteger(prefs::kLoFiConsecutiveSessionDisables) + 1);
+  }
+}
+
 void DataReductionProxySettings::RegisterDataReductionProxyFieldTrial() {
   register_synthetic_field_trial_.Run(
       "SyntheticDataReductionProxySetting",
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h
index 8e65315..29ff6be 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h
@@ -115,6 +115,11 @@ class DataReductionProxySettings : public DataReductionProxyServiceObserver {
   // context menu request has been made since the last main frame request.
   void SetLoFiShowImageRequested();
 
+  // Counts the number of requests to reload the page with images from the Lo-Fi
+  // snackbar. If the user requests the page with images a certain number of
+  // times, then Lo-Fi is disabled for the session.
+  void IncrementLoFiUserRequestsForImages();
+
   // Returns the time in microseconds that the last update was made to the
   // daily original and received content lengths.
   int64 GetDataReductionLastUpdateTime();
@@ -217,6 +222,10 @@ class DataReductionProxySettings : public DataReductionProxyServiceObserver {
                            TestInitDataReductionProxyOff);
   FRIEND_TEST_ALL_PREFIXES(DataReductionProxySettingsTest,
                            CheckInitMetricsWhenNotAllowed);
+  FRIEND_TEST_ALL_PREFIXES(DataReductionProxySettingsTest,
+                           TestLoFiImplicitOptOutClicksPerSession);
+  FRIEND_TEST_ALL_PREFIXES(DataReductionProxySettingsTest,
+                           TestLoFiImplicitOptOutConsecutiveSessions);
 
   // Override of DataReductionProxyService::Observer.
   void OnServiceInitialized() override;
@@ -265,6 +274,10 @@ class DataReductionProxySettings : public DataReductionProxyServiceObserver {
   // last main frame request.
   bool lo_fi_show_image_requested_;
 
+  // The number of requests to reload the page with images from the Lo-Fi
+  // snackbar until Lo-Fi is disabled.
+  int lo_fi_user_requests_for_images_per_session_;
+
   BooleanPrefMember spdy_proxy_auth_enabled_;
   BooleanPrefMember data_reduction_proxy_alternative_enabled_;
 
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings_unittest.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings_unittest.cc
index 8c9d34e..2779bfc 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings_unittest.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_settings_unittest.cc
@@ -336,6 +336,120 @@ TEST_F(DataReductionProxySettingsTest, TestEnableLoFiSyntheticTrial) {
   CheckDataReductionProxyLoFiSyntheticTrial(false);
 }
 
+TEST_F(DataReductionProxySettingsTest, TestLoFiImplicitOptOutClicksPerSession) {
+  test_context_->config()->ResetLoFiStatusForTest();
+  EXPECT_EQ(0, test_context_->pref_service()->GetInteger(
+                   prefs::kLoFiLoadImagesPerSession));
+  EXPECT_EQ(LoFiStatus::LOFI_STATUS_TEMPORARILY_OFF,
+            test_context_->config()->GetLoFiStatus());
+
+  // Click "Show images" |lo_fi_user_requests_for_images_per_session_| times.
+  for (int i = 1; i <= settings_->lo_fi_user_requests_for_images_per_session_;
+       ++i) {
+    settings_->IncrementLoFiUserRequestsForImages();
+    EXPECT_EQ(i, test_context_->pref_service()->GetInteger(
+                     prefs::kLoFiLoadImagesPerSession));
+  }
+
+  test_context_->RunUntilIdle();
+  EXPECT_EQ(1, test_context_->pref_service()->GetInteger(
+                   prefs::kLoFiConsecutiveSessionDisables));
+  EXPECT_EQ(LoFiStatus::LOFI_STATUS_OFF,
+            test_context_->config()->GetLoFiStatus());
+
+  // Reset the opt out pref values and config Lo-Fi status as if we're starting
+  // a new session.
+  test_context_->config()->ResetLoFiStatusForTest();
+  settings_->data_reduction_proxy_service_->InitializeLoFiPrefs();
+  EXPECT_EQ(0, test_context_->pref_service()->GetInteger(
+                   prefs::kLoFiLoadImagesPerSession));
+  EXPECT_EQ(LoFiStatus::LOFI_STATUS_TEMPORARILY_OFF,
+            test_context_->config()->GetLoFiStatus());
+
+  // Have a session that doesn't have
+  // |lo_fi_user_requests_for_images_per_session_| so
+  // kLoFiConsecutiveSessionDisables resets.
+  for (int i = 1;
+       i <= settings_->lo_fi_user_requests_for_images_per_session_ - 1; ++i) {
+    settings_->IncrementLoFiUserRequestsForImages();
+    EXPECT_EQ(i, test_context_->pref_service()->GetInteger(
+                     prefs::kLoFiLoadImagesPerSession));
+  }
+
+  test_context_->RunUntilIdle();
+  // Still should have only one consecutive session disable and Lo-Fi status
+  // shouldn't have been set to off.
+  EXPECT_EQ(1, test_context_->pref_service()->GetInteger(
+                   prefs::kLoFiConsecutiveSessionDisables));
+  EXPECT_EQ(LoFiStatus::LOFI_STATUS_TEMPORARILY_OFF,
+            test_context_->config()->GetLoFiStatus());
+
+  // Start a new session. The consecutive session count should now be reset to
+  // zero.
+  test_context_->config()->ResetLoFiStatusForTest();
+  settings_->data_reduction_proxy_service_->InitializeLoFiPrefs();
+  EXPECT_EQ(0, test_context_->pref_service()->GetInteger(
+                   prefs::kLoFiConsecutiveSessionDisables));
+}
+
+TEST_F(DataReductionProxySettingsTest,
+       TestLoFiImplicitOptOutConsecutiveSessions) {
+  test_context_->config()->ResetLoFiStatusForTest();
+  EXPECT_EQ(0, test_context_->pref_service()->GetInteger(
+                   prefs::kLoFiLoadImagesPerSession));
+  EXPECT_EQ(0, test_context_->pref_service()->GetInteger(
+                   prefs::kLoFiConsecutiveSessionDisables));
+  EXPECT_EQ(LoFiStatus::LOFI_STATUS_TEMPORARILY_OFF,
+            test_context_->config()->GetLoFiStatus());
+
+  // Disable Lo-Fi for 3 consecutive sessions.
+  for (int i = 1; i <= 3; ++i) {
+    // Start a new session.
+    test_context_->config()->ResetLoFiStatusForTest();
+    settings_->data_reduction_proxy_service_->InitializeLoFiPrefs();
+    EXPECT_EQ(LoFiStatus::LOFI_STATUS_TEMPORARILY_OFF,
+              test_context_->config()->GetLoFiStatus());
+
+    // Click "Show images" |lo_fi_user_requests_for_images_per_session_| times
+    // for each session.
+    for (int j = 1; j <= settings_->lo_fi_user_requests_for_images_per_session_;
+         ++j) {
+      settings_->IncrementLoFiUserRequestsForImages();
+      EXPECT_EQ(j, test_context_->pref_service()->GetInteger(
+                       prefs::kLoFiLoadImagesPerSession));
+    }
+
+    test_context_->RunUntilIdle();
+    EXPECT_EQ(i, test_context_->pref_service()->GetInteger(
+                     prefs::kLoFiConsecutiveSessionDisables));
+    EXPECT_EQ(LoFiStatus::LOFI_STATUS_OFF,
+              test_context_->config()->GetLoFiStatus());
+  }
+
+  // Start a new session. Lo-Fi should be set off.
+  test_context_->config()->ResetLoFiStatusForTest();
+  settings_->data_reduction_proxy_service_->InitializeLoFiPrefs();
+  test_context_->RunUntilIdle();
+  EXPECT_EQ(3, test_context_->pref_service()->GetInteger(
+                   prefs::kLoFiConsecutiveSessionDisables));
+  EXPECT_EQ(LoFiStatus::LOFI_STATUS_OFF,
+            test_context_->config()->GetLoFiStatus());
+
+  // Set the implicit opt out version to -1 so that the default value of zero
+  // will be an increase and the opt out status will be reset.
+  test_context_->pref_service()->SetInteger(prefs::kLoFiImplicitOptOutVersion,
+                                            -1);
+
+  // Start a new session. Lo-Fi should be set on again.
+  test_context_->config()->ResetLoFiStatusForTest();
+  settings_->data_reduction_proxy_service_->InitializeLoFiPrefs();
+  test_context_->RunUntilIdle();
+  EXPECT_EQ(0, test_context_->pref_service()->GetInteger(
+                   prefs::kLoFiConsecutiveSessionDisables));
+  EXPECT_EQ(LoFiStatus::LOFI_STATUS_TEMPORARILY_OFF,
+            test_context_->config()->GetLoFiStatus());
+}
+
 TEST_F(DataReductionProxySettingsTest, TestGetDailyContentLengths) {
   ContentLengthList result =
       settings_->GetDailyContentLengths(prefs::kDailyHttpOriginalContentLength);
diff --git a/components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc b/components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc
index 8893fcb..24c108d 100644
--- a/components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc
+++ b/components/data_reduction_proxy/core/common/data_reduction_proxy_params.cc
@@ -10,6 +10,7 @@
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/values.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_client_config_parser.h"
@@ -211,6 +212,20 @@ bool DataReductionProxyParams::ShouldUseSecureProxyByDefault() {
   return true;
 }
 
+// static
+int DataReductionProxyParams::GetFieldTrialParameterAsInteger(
+    const std::string& group,
+    const std::string& param_name,
+    int default_value) {
+  std::string param_value =
+      variations::GetVariationParamValue(group, param_name);
+  int value;
+  if (param_value.empty() || !base::StringToInt(param_value, &value))
+    return default_value;
+
+  return value;
+}
+
 void DataReductionProxyParams::EnableQuic(bool enable) {
   quic_enabled_ = enable;
   DCHECK(!quic_enabled_ || IsIncludedInQuicFieldTrial());
diff --git a/components/data_reduction_proxy/core/common/data_reduction_proxy_params.h b/components/data_reduction_proxy/core/common/data_reduction_proxy_params.h
index 05e2fe1..b4ada80 100644
--- a/components/data_reduction_proxy/core/common/data_reduction_proxy_params.h
+++ b/components/data_reduction_proxy/core/common/data_reduction_proxy_params.h
@@ -136,6 +136,13 @@ class DataReductionProxyParams : public DataReductionProxyConfigValues {
   // secure proxy check fails.
   static bool ShouldUseSecureProxyByDefault();
 
+  // Retrieves the int stored in |param_name| from the field trial group
+  // |group|. If the value is not present or cannot be parsed returns
+  // |default_value|.
+  static int GetFieldTrialParameterAsInteger(const std::string& group,
+                                             const std::string& param_name,
+                                             int default_value);
+
   // Constructs configuration parameters. If |kAllowed|, then the standard
   // data reduction proxy configuration is allowed to be used. If
   // |kfallbackAllowed| a fallback proxy can be used if the primary proxy is
diff --git a/components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.cc b/components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.cc
index 5164895..46d1f0d5 100644
--- a/components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.cc
+++ b/components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.cc
@@ -91,6 +91,22 @@ const char kHttpReceivedContentLength[] = "http_received_content_length";
 // received over the network.
 const char kHttpOriginalContentLength[] = "http_original_content_length";
 
+// An integer pref that contains the Lo-Fi version for the implicit opt-out
+// rules. Any time this value is incremented via Finch,
+// kLoFiConsecutiveSessionDisables is reset to zero.
+const char kLoFiImplicitOptOutVersion[] =
+    "data_reduction_lo_fi.implicit_opt_out_version";
+
+// An integer pref that contains the number of times that "Load images" has been
+// requested on the Lo-Fi snackbar for the current session.
+const char kLoFiLoadImagesPerSession[] =
+    "data_reduction_lo_fi.load_images_requests_per_session";
+
+// An integer pref that contains the number of consecutive sessions that LoFi
+// has been disabled.
+const char kLoFiConsecutiveSessionDisables[] =
+    "data_reduction_lo_fi.consecutive_session_disables";
+
 // Pref to store the retrieval time of the last simulated Data Reduction Proxy
 // configuration. This is part of an experiment to see how many bytes are lost
 // if the Data Reduction Proxy is not used due to configuration being expired
diff --git a/components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.h b/components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.h
index 72116b5..df10c80 100644
--- a/components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.h
+++ b/components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.h
@@ -29,6 +29,9 @@ extern const char kDataReductionProxyAltEnabled[];
 extern const char kDataReductionProxyWasEnabledBefore[];
 extern const char kHttpOriginalContentLength[];
 extern const char kHttpReceivedContentLength[];
+extern const char kLoFiImplicitOptOutVersion[];
+extern const char kLoFiLoadImagesPerSession[];
+extern const char kLoFiConsecutiveSessionDisables[];
 extern const char kSimulatedConfigRetrieveTime[];
 extern const char kStatisticsPrefsMigrated[];
 extern const char kUpdateDailyReceivedContentLengths[];