WebApps: Add flag for experimenting with adding tab strips to PWA windows

This CL adds a DesktopPWAsTabStrip flag that's disabled by default which
adds Chrome's tab strip UI to PWA windows.
This is purely for experimentation and communication with UX.

Screenshot: https://bugs.chromium.org/p/chromium/issues/attachment?aid=424245&signed_aid=oQpgjaC2V3-UC0L_ziRbsg==&inline=1

Bug: 1020050
Change-Id: Icd19f9ba58b60c5c9b042fcf3c6325a2c7a555f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1950727
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Raymes Khoury <raymes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729643}

chrome/browser/about_flags.cc

@@ -2234,6 +2234,10 @@ const FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kDesktopPWAsLocalUpdatingName,
      flag_descriptions::kDesktopPWAsLocalUpdatingDescription, kOsDesktop,
      FEATURE_VALUE_TYPE(features::kDesktopPWAsLocalUpdating)},
+    {"enable-desktop-pwas-tab-strip",
+     flag_descriptions::kDesktopPWAsTabStripName,
+     flag_descriptions::kDesktopPWAsTabStripDescription, kOsDesktop,
+     FEATURE_VALUE_TYPE(features::kDesktopPWAsTabStrip)},
     {"enable-system-webapps", flag_descriptions::kEnableSystemWebAppsName,
      flag_descriptions::kEnableSystemWebAppsDescription, kOsDesktop,
      FEATURE_VALUE_TYPE(features::kSystemWebApps)},

chrome/browser/flag-metadata.json

@@ -1253,6 +1253,11 @@
     "owners": [ "desktop-pwas-team@google.com" ],
     "expiry_milestone": 83
   },
+  {
+    "name": "enable-desktop-pwas-tab-strip",
+    "owners": [ "desktop-pwas-team@google.com" ],
+    "expiry_milestone": 84
+  },
   {
     "name": "enable-devtools-experiments",
     "owners": [ "//third_party/devtools-frontend/src/OWNERS" ],

chrome/browser/flag_descriptions.cc

@@ -644,6 +644,11 @@ extern const char kDesktopPWAsLocalUpdatingDescription[] =
     "Enable installed PWAs to update their app manifest data when the site "
     "manifest data has changed.";
 
+extern const char kDesktopPWAsTabStripName[] = "Desktop PWA tab strips";
+extern const char kDesktopPWAsTabStripDescription[] =
+    "Experimental UI for exploring what PWA windows would look like with a tab "
+    "strip.";
+
 const char kEnableSystemWebAppsName[] = "System Web Apps";
 const char kEnableSystemWebAppsDescription[] =
     "Experimental system for using the Desktop PWA framework for running System"

chrome/browser/flag_descriptions.h

@@ -398,6 +398,9 @@ extern const char kEnableDesktopPWAsDescription[];
 extern const char kDesktopPWAsLocalUpdatingName[];
 extern const char kDesktopPWAsLocalUpdatingDescription[];
 
+extern const char kDesktopPWAsTabStripName[];
+extern const char kDesktopPWAsTabStripDescription[];
+
 extern const char kEnableSystemWebAppsName[];
 extern const char kEnableSystemWebAppsDescription[];
 

chrome/browser/ui/web_applications/app_browser_controller.cc

@@ -94,7 +94,9 @@ AppBrowserController::AppBrowserController(
       // Show tabs for Terminals only.
       // TODO(crbug.com/846546): Generalise has_tab_strip_ as a SystemWebApp
       // capability.
-      has_tab_strip_(system_app_type_ == SystemAppType::TERMINAL) {
+      has_tab_strip_(
+          base::FeatureList::IsEnabled(features::kDesktopPWAsTabStrip) ||
+          system_app_type_ == SystemAppType::TERMINAL) {
   browser->tab_strip_model()->AddObserver(this);
 }
 

chrome/common/chrome_features.cc

@@ -262,6 +262,10 @@ const base::Feature kDesktopPWAsCacheDuringDefaultInstall{
 const base::Feature kDesktopPWAsLocalUpdating{"DesktopPWAsLocalUpdating",
                                               base::FEATURE_ENABLED_BY_DEFAULT};
 
+// Adds a tab strip to PWA windows, used for UI experimentation.
+const base::Feature kDesktopPWAsTabStrip{"DesktopPWAsTabStrip",
+                                         base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Enables or disables use of new Desktop PWAs browser controller (that uses the
 // universal web_app::AppRegistrar) by extensions-based bookmark apps. Note that
 // the new Desktop PWAs implementation (not based on extensions) always uses the

chrome/common/chrome_features.h

@@ -146,6 +146,9 @@ extern const base::Feature kDesktopPWAsCacheDuringDefaultInstall;
 COMPONENT_EXPORT(CHROME_FEATURES)
 extern const base::Feature kDesktopPWAsLocalUpdating;
 
+COMPONENT_EXPORT(CHROME_FEATURES)
+extern const base::Feature kDesktopPWAsTabStrip;
+
 COMPONENT_EXPORT(CHROME_FEATURES)
 extern const base::Feature kDesktopPWAsUnifiedUiController;
 

tools/metrics/histograms/enums.xml

@@ -36419,6 +36419,7 @@ from previous Chrome versions.
   <int value="-1872989945" label="enable-webview-based-signin"/>
   <int value="-1872867546" label="EnumerateAudioDevices:disabled"/>
   <int value="-1872205507" label="ShelfNewUi:enabled"/>
+  <int value="-1871552967" label="DesktopPWAsTabStrip:disabled"/>
   <int value="-1871185948" label="VrLaunchIntents:disabled"/>
   <int value="-1870961970" label="enable-filemanager-mtp"/>
   <int value="-1869845022" label="force-show-update-menu-item"/>
@@ -37795,6 +37796,7 @@ from previous Chrome versions.
   <int value="-141516902" label="UseModernMediaControls:enabled"/>
   <int value="-140168253" label="ProfileMenuRevamp:enabled"/>
   <int value="-138983372" label="DesktopPWAWindowing:disabled"/>
+  <int value="-138820512" label="DesktopPWAsTabStrip:enabled"/>
   <int value="-138773929" label="PassiveDocumentEventListeners:enabled"/>
   <int value="-138760381" label="AutofillManualFallbackAndroid:enabled"/>
   <int value="-137303226" label="enable-chromevox-developer-option"/>