Experiment for showing the Tab Switcher on returning to Chrome.

Adding a utility class to handle the logic of calculating if enough time
has passed. The last backgrounded time is already tracked in
ChromeTabbedActivity::onStopWithNative().

Experiment name is enable-tab-switcher-on-return. See `chrome://flags`

Available options are 30 or 60 minutes.

R=yusufo@chromium.org

Bug: 898685
Change-Id: I916eb86b55525f06335d27cec84de78b1e366e98
Reviewed-on: https://chromium-review.googlesource.com/c/1384658Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Commit-Queue: Matt Simmons <mattsimmons@google.com>
Cr-Commit-Position: refs/heads/master@{#618309}

chrome/android/java/src/org/chromium/chrome/browser/ChromeFeatureList.java

@@ -277,6 +277,7 @@ public abstract class ChromeFeatureList {
     public static final String SUBRESOURCE_FILTER = "SubresourceFilter";
     public static final String QUERY_IN_OMNIBOX = "QueryInOmnibox";
     public static final String TAB_REPARENTING = "TabReparenting";
+    public static final String TAB_SWITCHER_ON_RETURN = "TabSwitcherOnReturn";
     public static final String TRANSLATE_ANDROID_MANUAL_TRIGGER = "TranslateAndroidManualTrigger";
     public static final String TRUSTED_WEB_ACTIVITY = "TrustedWebActivity";
     public static final String TRUSTED_WEB_ACTIVITY_POST_MESSAGE = "TrustedWebActivityPostMessage";

chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity.java

@@ -785,6 +785,16 @@ public class ChromeTabbedActivity
 
     private void setInitialOverviewState() {
         boolean isOverviewVisible = mLayoutManager.overviewVisible();
+
+        // Experiment: show tab switcher on return after {x} minutes (enable-tab-switcher-on-return}
+        long lastBackgroundedTimeMillis =
+                ContextUtils.getAppSharedPreferences().getLong(LAST_BACKGROUNDED_TIME_MS_PREF, -1);
+        if (ReturnToChromeExperimentsUtil.shouldShowTabSwitcher(lastBackgroundedTimeMillis)
+                && !isOverviewVisible) {
+            toggleOverview();
+            return;
+        }
+
         if (getActivityTab() == null && !isOverviewVisible) {
             toggleOverview();
         }

chrome/android/java/src/org/chromium/chrome/browser/ReturnToChromeExperimentsUtil.java

+// Copyright 2018 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.
+
+package org.chromium.chrome.browser;
+
+/**
+ * This is a utility class for managing experiments related to returning to Chrome.
+ */
+final class ReturnToChromeExperimentsUtil {
+    private static final String TAB_SWITCHER_ON_RETURN_MS = "tab_switcher_on_return_time_ms";
+
+    private ReturnToChromeExperimentsUtil() {}
+
+    /**
+     * Determine if we should show the tab switcher on returning to Chrome.
+     *   Returns true if enough time has elapsed since the app was last backgrounded.
+     *   The threshold time in milliseconds is set by experiment "enable-tab-switcher-on-return"
+     *
+     * @param lastBackgroundedTimeMillis The last time the application was backgrounded. Set in
+     *                                   ChromeTabbedActivity::onStopWithNative
+     * @return true if past threshold, false if not past threshold or experiment cannot be loaded.
+     */
+    static boolean shouldShowTabSwitcher(final long lastBackgroundedTimeMillis) {
+        if (lastBackgroundedTimeMillis == -1) {
+            // No last background timestamp set, use control behavior.
+            return false;
+        }
+
+        int tabSwitcherAfterMillis = ChromeFeatureList.getFieldTrialParamByFeatureAsInt(
+                ChromeFeatureList.TAB_SWITCHER_ON_RETURN, TAB_SWITCHER_ON_RETURN_MS, -1);
+
+        if (tabSwitcherAfterMillis < 0) {
+            // If no value for experiment, use control behavior.
+            return false;
+        }
+
+        long expirationTime = lastBackgroundedTimeMillis + tabSwitcherAfterMillis;
+
+        return System.currentTimeMillis() > expirationTime;
+    }
+}

chrome/android/java_sources.gni

@@ -63,6 +63,7 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/PowerBroadcastReceiver.java",
   "java/src/org/chromium/chrome/browser/RepostFormWarningDialog.java",
   "java/src/org/chromium/chrome/browser/SSLClientCertificateRequest.java",
+  "java/src/org/chromium/chrome/browser/ReturnToChromeExperimentsUtil.java",
   "java/src/org/chromium/chrome/browser/SearchGeolocationDisclosureTabHelper.java",
   "java/src/org/chromium/chrome/browser/ServiceTabLauncher.java",
   "java/src/org/chromium/chrome/browser/ShortcutHelper.java",

chrome/browser/about_flags.cc

@@ -1185,6 +1185,19 @@ const FeatureEntry::FeatureVariation kOfflineIndicatorFeatureVariations[] = {
      base::size(kBottomOfflineIndicatorEnabled), nullptr}};
 #endif  // OS_ANDROID
 
+#if defined(OS_ANDROID)
+const FeatureEntry::FeatureParam kTabSwitcherOnReturn_30Minutes[] = {
+    {"tab_switcher_on_return_time_ms", "1800000"}};
+const FeatureEntry::FeatureParam kTabSwitcherOnReturn_60Minutes[] = {
+    {"tab_switcher_on_return_time_ms", "3600000"}};
+const FeatureEntry::FeatureVariation kTabSwitcherOnReturnVariations[] = {
+    {"30 minutes", kTabSwitcherOnReturn_30Minutes,
+     base::size(kTabSwitcherOnReturn_30Minutes), nullptr},
+    {"60 minutes", kTabSwitcherOnReturn_60Minutes,
+     base::size(kTabSwitcherOnReturn_60Minutes), nullptr},
+};
+#endif  // OS_ANDROID
+
 // RECORDING USER METRICS FOR FLAGS:
 // -----------------------------------------------------------------------------
 // The first line of the entry is the internal name.
@@ -3690,6 +3703,15 @@ const FeatureEntry kFeatureEntries[] = {
      FEATURE_VALUE_TYPE(chrome::android::kHorizontalTabSwitcherAndroid)},
 #endif  // OS_ANDROID
 
+#if defined(OS_ANDROID)
+    {"enable-tab-switcher-on-return",
+     flag_descriptions::kTabSwitcherOnReturnName,
+     flag_descriptions::kTabSwitcherOnReturnDescription, kOsAndroid,
+     FEATURE_WITH_PARAMS_VALUE_TYPE(chrome::android::kTabSwitcherOnReturn,
+                                    kTabSwitcherOnReturnVariations,
+                                    "TabSwitcherOnReturn")},
+#endif
+
 #if defined(OS_CHROMEOS)
     {"enable-apps-grid-gap", flag_descriptions::kEnableAppsGridGapFeatureName,
      flag_descriptions::kEnableAppsGridGapFeatureDescription, kOsCrOS,

chrome/browser/android/chrome_feature_list.cc

@@ -144,6 +144,7 @@ const base::Feature* kFeaturesExposedToJava[] = {
     &kSpecialLocaleFeature,
     &kSpecialLocaleWrapper,
     &kTabReparenting,
+    &kTabSwitcherOnReturn,
     &kTrustedWebActivity,
     &kTrustedWebActivityPostMessage,
     &kVideoPersistence,
@@ -405,6 +406,9 @@ const base::Feature kSpecialLocaleWrapper{"SpecialLocaleWrapper",
 const base::Feature kTabReparenting{"TabReparenting",
                                     base::FEATURE_ENABLED_BY_DEFAULT};
 
+const base::Feature kTabSwitcherOnReturn{"TabSwitcherOnReturn",
+                                         base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kTrustedWebActivity{"TrustedWebActivity",
                                         base::FEATURE_ENABLED_BY_DEFAULT};
 

chrome/browser/android/chrome_feature_list.h

@@ -81,6 +81,7 @@ extern const base::Feature kSpannableInlineAutocomplete;
 extern const base::Feature kSpecialLocaleFeature;
 extern const base::Feature kSpecialLocaleWrapper;
 extern const base::Feature kTabReparenting;
+extern const base::Feature kTabSwitcherOnReturn;
 extern const base::Feature kTrustedWebActivity;
 extern const base::Feature kTrustedWebActivityPostMessage;
 extern const base::Feature kUserMediaScreenCapturing;

chrome/browser/flag-metadata.json

@@ -1919,6 +1919,11 @@
     // "owners": [ "your-team" ],
     "expiry_milestone": 76
   },
+  {
+    "name": "enable-tab-switcher-on-return",
+    "owners": [ "memex-team@google.com" ],
+    "expiry_milestone": 76
+  },
   {
     "name": "enable-tcp-fast-open",
     // "owners": [ "your-team" ],

chrome/browser/flag_descriptions.cc

@@ -1091,6 +1091,10 @@ const char kHorizontalTabSwitcherAndroidDescription[] =
     "Changes the layout of the Android tab switcher so tabs scroll "
     "horizontally instead of vertically.";
 
+const char kTabSwitcherOnReturnName[] = "Enable tab switcher on return";
+const char kTabSwitcherOnReturnDescription[] =
+    "Enable tab switcher on return after specified time has elapsed";
+
 const char kHostedAppQuitNotificationName[] =
     "Quit notification for hosted apps";
 const char kHostedAppQuitNotificationDescription[] =

chrome/browser/flag_descriptions.h

@@ -650,6 +650,9 @@ extern const char kHarfbuzzRendertextDescription[];
 extern const char kHorizontalTabSwitcherAndroidName[];
 extern const char kHorizontalTabSwitcherAndroidDescription[];
 
+extern const char kTabSwitcherOnReturnName[];
+extern const char kTabSwitcherOnReturnDescription[];
+
 extern const char kViewsCastDialogName[];
 extern const char kViewsCastDialogDescription[];
 

tools/metrics/histograms/enums.xml

@@ -30421,6 +30421,7 @@ from previous Chrome versions.
   <int value="-1503851906" label="EnableSettingsShortcutSearch:enabled"/>
   <int value="-1498334893" label="ExperimentalVRFeatures:enabled"/>
   <int value="-1497338981" label="disable-accelerated-overflow-scroll"/>
+  <int value="-1492934655" label="TabSwitcherOnReturn:enabled"/>
   <int value="-1492589689" label="ContentSuggestionsCategories:enabled"/>
   <int value="-1491417046" label="enable-fullscreen-toolbar-reveal"/>
   <int value="-1491304576" label="ProgressBarThrottle:disabled"/>
@@ -32307,6 +32308,7 @@ from previous Chrome versions.
   <int value="1887882558" label="RTCUnifiedPlanByDefault:enabled"/>
   <int value="1888812860" label="ChromeModernAlternateCardLayout:enabled"/>
   <int value="1889076955" label="disable-app-link"/>
+  <int value="1889198874" label="TabSwitcherOnReturn:disabled"/>
   <int value="1891210939" label="enable-blink-features"/>
   <int value="1891312456" label="AndroidMessagesProdEndpoint:disabled"/>
   <int value="1892201400" label="enable-password-separated-signin-flow"/>