Adding an experiment to automatically open the default browser chooser

Bug: 798612
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ie9bb7d1af812a96f11058c928cb32fa6491d96db
Reviewed-on: https://chromium-review.googlesource.com/981079
Commit-Queue: Patrick Monette <pmonette@chromium.org>
Reviewed-by: Dominic Battré <battre@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Greg Thompson <grt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567797}

chrome/browser/prefs/browser_prefs.cc

@@ -339,6 +339,12 @@ const char kInstantUIZeroSuggestUrlPrefix[] =
 const char kTouchHudProjectionEnabled[] = "touch_hud.projection_enabled";
 #endif
 
+#if defined(OS_WIN)
+// Deprecated 6/2018.
+const char kResetHasSeenWin10PromoPage[] =
+    "browser.reset_has_seen_win10_promo_page";
+#endif
+
 // Register prefs used only for migration (clearing or moving to a new key).
 void RegisterProfilePrefsForMigration(
     user_prefs::PrefRegistrySyncable* registry) {
@@ -485,6 +491,8 @@ void RegisterLocalState(PrefRegistrySimple* registry) {
   ModuleDatabase::RegisterLocalStatePrefs(registry);
   ThirdPartyConflictsManager::RegisterLocalStatePrefs(registry);
 #endif  // defined(GOOGLE_CHROME_BUILD)
+
+  registry->RegisterBooleanPref(kResetHasSeenWin10PromoPage, false);
 #endif
 
 #if defined(TOOLKIT_VIEWS)
@@ -747,6 +755,11 @@ void MigrateObsoleteBrowserPrefs(Profile* profile, PrefService* local_state) {
   // Added 5/2018.
   local_state->ClearPref(prefs::kProblematicPrograms);
 #endif
+
+#if defined(OS_WIN)
+  // Added 6/2018.
+  local_state->ClearPref(kResetHasSeenWin10PromoPage);
+#endif
 }
 
 // This method should be periodically pruned of year+ old migrations.

chrome/browser/resources/welcome/welcome_win10.html

@@ -8,9 +8,12 @@
 
   <link rel="import" href="chrome://resources/cr_elements/icons.html">
   <link rel="import" href="chrome://resources/html/cr.html">
+  <link rel="import" href="chrome://resources/html/load_time_data.html">
+  <link rel="import" href="chrome://resources/html/util.html">
+
   <link rel="import" href="chrome://resources/html/action_link.html">
   <link rel="import" href="chrome://resources/html/action_link_css.html">
-  <link rel="import" href="chrome://resources/html/util.html">
+
   <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
   <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
   <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/color.html">
@@ -18,11 +21,12 @@
   <link rel="stylesheet" href="chrome://resources/css/text_defaults_md.css">
   <link rel="stylesheet" href="/welcome_win10.css">
 
+  <script src="strings.js"></script>
+
   <dom-module id="welcome-win10">
     <template>
       <style include="action-link">
         :host {
-          --expandable-section-height: 28.375em;
           align-items: flex-start;
           display: inline-flex;
           flex-direction: column;
@@ -31,6 +35,14 @@
           transition: opacity 300ms;
         }
 
+        :host .section {
+          --expandable-section-height: 28.375em;
+        }
+
+        :host([is-accelerated]) .section {
+          --expandable-section-height: 26.375em;
+        }
+
         a {
           color: var(--google-blue-500);
           text-decoration: none;
@@ -52,8 +64,10 @@
           margin: 0 -0.0625em;
         }
 
-        .heading {
+        h1 {
           font-size: 2.125em;
+          font-weight: normal;
+          margin: 0;
           padding-bottom: 2rem;
           padding-top: 1rem;
         }
@@ -274,7 +288,7 @@
         }
       </style>
       <div class="header-logo" role="presentation"></div>
-      <div class="heading">$i18n{headerText}</div>
+      <h1>$i18n{headerText}</h1>
       <div class="sections">
         <div class$="[[computeClasses(isCombined)]]">
           <template is="dom-if" if="[[isCombined]]">

chrome/browser/resources/welcome/welcome_win10.js

@@ -8,10 +8,19 @@ Polymer({
   properties: {
     // Determines if the combined variant should be displayed. The combined
     // variant includes instructions on how to pin Chrome to the taskbar.
-    isCombined: Boolean,
+    isCombined: {
+      type: Boolean,
+      value: false,
+    },
 
     // Indicates if the accelerated flow is enabled.
-    isAccelerated: Boolean,
+    isAccelerated: {
+      type: Boolean,
+      value: function() {
+        return loadTimeData.getBoolean('acceleratedFlowEnabled');
+      },
+      reflectToAttribute: true,
+    },
   },
 
   receivePinnedState_: function(isPinnedToTaskbar) {
@@ -30,21 +39,15 @@ Polymer({
   },
 
   ready: function() {
-    this.isCombined = false;
-    this.isAccelerated = false;
-
+    // The accelerated flow can be overridden with a query parameter.
     const FLOWTYPE_KEY = 'flowtype';
     const FLOW_TYPE_MAP = {'regular': false, 'accelerated': true};
     var params = new URLSearchParams(location.search);
     if (params.has(FLOWTYPE_KEY)) {
       if (params.get(FLOWTYPE_KEY) in FLOW_TYPE_MAP) {
         this.isAccelerated = FLOW_TYPE_MAP[params.get(FLOWTYPE_KEY)];
-
-        // Adjust the height since the accelerated flow contains fewer steps.
-        this.customStyle['--expandable-section-height'] = '26.375em';
-        this.updateStyles();
       } else {
-        console.log(
+        console.error(
             'Found invalid value for the \'flowtype\' parameter: %s',
             params.get(FLOWTYPE_KEY));
       }

chrome/browser/ui/webui/welcome_win10_ui.cc

@@ -11,6 +11,7 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/welcome_win10_handler.h"
+#include "chrome/common/chrome_features.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/browser_resources.h"
@@ -87,8 +88,15 @@ WelcomeWin10UI::WelcomeWin10UI(content::WebUI* web_ui, const GURL& url)
   content::WebUIDataSource* html_source =
       content::WebUIDataSource::Create(url.host());
 
+  html_source->SetJsonPath("strings.js");
+
   AddLocalizedStrings(html_source, is_first_run);
 
+  // Controls the accelerated default browser flow experiment.
+  html_source->AddBoolean("acceleratedFlowEnabled",
+                          base::FeatureList::IsEnabled(
+                              features::kWin10AcceleratedDefaultBrowserFlow));
+
   html_source->AddResourcePath("welcome_win10.css", IDR_WELCOME_WIN10_CSS);
   html_source->AddResourcePath("welcome_win10.js", IDR_WELCOME_WIN10_JS);
   html_source->AddResourcePath("default.webp", IDR_WELCOME_WIN10_DEFAULT_WEBP);

chrome/browser/win/settings_app_monitor.cc

@@ -9,8 +9,10 @@
 #include <utility>
 
 #include "base/bind.h"
+#include "base/feature_list.h"
 #include "base/location.h"
 #include "base/memory/scoped_refptr.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/sequenced_task_runner.h"
 #include "base/strings/pattern.h"
 #include "base/strings/string16.h"
@@ -19,6 +21,7 @@
 #include "base/win/scoped_variant.h"
 #include "chrome/browser/win/automation_controller.h"
 #include "chrome/browser/win/ui_automation_util.h"
+#include "chrome/common/chrome_features.h"
 
 namespace {
 
@@ -43,6 +46,7 @@ void ConfigureCacheRequest(IUIAutomationCacheRequest* cache_request) {
   cache_request->AddProperty(UIA_AutomationIdPropertyId);
   cache_request->AddProperty(UIA_NamePropertyId);
   cache_request->AddProperty(UIA_ClassNamePropertyId);
+  cache_request->AddPattern(UIA_InvokePatternId);
 }
 
 // Helper function to get the parent element with class name "Flyout". Used to
@@ -123,6 +127,10 @@ class SettingsAppMonitor::AutomationControllerDelegate
                            IUIAutomationElement* sender) const override;
 
  private:
+  // Invokes the |browser_button| if the Win10AcceleratedDefaultBrowserFlow
+  // feature is enabled.
+  void MaybeInvokeChooser(IUIAutomationElement* browser_button) const;
+
   // The task runner on which the SettingsAppMonitor lives.
   const scoped_refptr<base::SequencedTaskRunner> monitor_runner_;
 
@@ -135,6 +143,12 @@ class SettingsAppMonitor::AutomationControllerDelegate
   // State to suppress duplicate "focus changed" events.
   mutable ElementType last_focused_element_;
 
+  // Protect against concurrent accesses to |browser_chooser_invoked_|.
+  mutable base::Lock browser_chooser_invoked_lock_;
+
+  // The browser chooser must only be invoked once.
+  mutable bool browser_chooser_invoked_;
+
   DISALLOW_COPY_AND_ASSIGN(AutomationControllerDelegate);
 };
 
@@ -143,7 +157,8 @@ SettingsAppMonitor::AutomationControllerDelegate::AutomationControllerDelegate(
     base::WeakPtr<SettingsAppMonitor> monitor)
     : monitor_runner_(monitor_runner),
       monitor_(std::move(monitor)),
-      last_focused_element_(ElementType::UNKNOWN) {}
+      last_focused_element_(ElementType::UNKNOWN),
+      browser_chooser_invoked_(false) {}
 
 SettingsAppMonitor::AutomationControllerDelegate::
     ~AutomationControllerDelegate() = default;
@@ -208,6 +223,7 @@ void SettingsAppMonitor::AutomationControllerDelegate::OnFocusChangedEvent(
   }
 
   if (element_type == ElementType::DEFAULT_BROWSER) {
+    MaybeInvokeChooser(sender);
     monitor_runner_->PostTask(
         FROM_HERE, base::BindOnce(&SettingsAppMonitor::OnAppFocused, monitor_));
   } else if (element_type == ElementType::CHECK_IT_OUT) {
@@ -217,6 +233,30 @@ void SettingsAppMonitor::AutomationControllerDelegate::OnFocusChangedEvent(
   }
 }
 
+void SettingsAppMonitor::AutomationControllerDelegate::MaybeInvokeChooser(
+    IUIAutomationElement* browser_button) const {
+  if (!base::FeatureList::IsEnabled(
+          features::kWin10AcceleratedDefaultBrowserFlow)) {
+    return;
+  }
+
+  {
+    // Only invoke the browser chooser once.
+    base::AutoLock auto_lock(browser_chooser_invoked_lock_);
+    if (browser_chooser_invoked_)
+      return;
+    browser_chooser_invoked_ = true;
+  }
+
+  // Invoke the dialog and record whether it was successful.
+  Microsoft::WRL::ComPtr<IUIAutomationInvokePattern> invoke_pattern;
+  bool succeeded = SUCCEEDED(browser_button->GetCachedPatternAs(
+                       UIA_InvokePatternId, IID_PPV_ARGS(&invoke_pattern))) &&
+                   invoke_pattern && SUCCEEDED(invoke_pattern->Invoke());
+
+  UMA_HISTOGRAM_BOOLEAN("DefaultBrowser.Win10ChooserInvoked", succeeded);
+}
+
 SettingsAppMonitor::SettingsAppMonitor(Delegate* delegate)
     : delegate_(delegate), weak_ptr_factory_(this) {
   // A fully initialized WeakPtrFactory is needed to create the

chrome/common/chrome_features.cc

@@ -625,4 +625,10 @@ const base::Feature kCrOSEnableUSMUserService{"CrOSEnableUSMUserService",
 
 #endif  // defined(OS_CHROMEOS)
 
+#if defined(OS_WIN)
+// Enables the accelerated default browser flow for Windows 10.
+const base::Feature kWin10AcceleratedDefaultBrowserFlow{
+    "Win10AcceleratedDefaultBrowserFlow", base::FEATURE_DISABLED_BY_DEFAULT};
+#endif  // defined(OS_WIN)
+
 }  // namespace features

chrome/common/chrome_features.h

@@ -339,6 +339,10 @@ extern const base::Feature kTPMFirmwareUpdate;
 extern const base::Feature kCrOSEnableUSMUserService;
 #endif  // defined(OS_CHROMEOS)
 
+#if defined(OS_WIN)
+extern const base::Feature kWin10AcceleratedDefaultBrowserFlow;
+#endif  // defined(OS_WIN)
+
 bool PrefServiceEnabled();
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in

testing/variations/fieldtrial_testing_config.json

@@ -4680,6 +4680,21 @@
             ]
         }
     ],
+    "Win10AcceleratedDefaultBrowserFlow": [
+        {
+            "platforms": [
+                "win"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "Win10AcceleratedDefaultBrowserFlow"
+                    ]
+                }
+            ]
+        }
+    ],
     "WorkStealingInScriptRunner": [
         {
             "platforms": [

tools/metrics/histograms/histograms.xml

@@ -16672,6 +16672,16 @@ uploading your change for review.
   <summary>Whether Chrome was the default browser when it started up.</summary>
 </histogram>
 
+<histogram name="DefaultBrowser.Win10ChooserInvoked" enum="BooleanSuccess">
+  <owner>pmonette@chromium.org</owner>
+  <summary>
+    When changing the default browser on Windows 10, records whether the browser
+    chooser is successfully invoked when opening the settings page. This
+    histogram is only recorded when the Win10AcceleratedDefaultBrowserFlow
+    experiment is enabled.
+  </summary>
+</histogram>
+
 <histogram name="DefaultBrowserWarning.DontSetAsDefault" enum="BooleanHit">
   <obsolete>
     Deprecated 2015/11. The same information is available as the value Failure