Determine the Win10-specific Welcome page variant to display

chrome/browser/ui/webui/welcome_win10_ui.cc

 // Copyright 2016 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.
 
 #include "chrome/browser/ui/webui/welcome_win10_ui.h"
 
 #include <string>
 
+#include "base/feature_list.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/welcome_win10_handler.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/browser_resources.h"
 #include "chrome/grit/chrome_unscaled_resources.h"
 #include "chrome/grit/chromium_strings.h"
 #include "chrome/grit/generated_resources.h"
 #include "chrome/grit/theme_resources.h"
 #include "content/public/browser/web_ui_data_source.h"
 #include "net/base/url_util.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "url/gurl.h"
 
 namespace {
 
 // Helper function to check the presence of a key/value inside the query in the
 // |url|.
 bool UrlContainsKeyValueInQuery(const GURL& url,
                                 const std::string& key,
                                 const std::string& expected_value) {
   std::string value;
   return net::GetValueForKeyInQuery(url, key, &value) &&
          value == expected_value;
 }
 
+bool ShouldShouldInlineStyleVariant(const GURL& url) {

[tmartino, 2016/10/28 15:18:04]

ShouldShould -> ShouldShow?

[Patrick Monette, 2016/10/28 21:21:37]

Done.

+  constexpr base::Feature kWelcomeWin10InlineStyle{

[tmartino, 2016/10/28 15:18:04]

Let's put this (and any other variations/experiments/etc. relating to
startup/first run) in
https://cs.chromium.org/chromium/src/chrome/browser/ui/startup/startup_featur...

I made it just for this :)

[Patrick Monette, 2016/10/28 21:21:37]

Done.

+      "WelcomeWin10InlineStyle", base::FEATURE_DISABLED_BY_DEFAULT};
+
+  // Can be overridden via a query.
+  if (UrlContainsKeyValueInQuery(url, "style", "inline"))
+    return true;
+  if (UrlContainsKeyValueInQuery(url, "style", "sectioned"))
+    return false;
+
+  return base::FeatureList::IsEnabled(kWelcomeWin10InlineStyle);
+}
+
 // Adds all the needed localized strings to |html_source|, depending on
 // the value of |is_first_run|.
 void AddLocalizedStrings(content::WebUIDataSource* html_source,
                          bool is_first_run) {
   // Only show the "Welcome to Chrome" text on first run.
   int welcome_header_id = is_first_run
                               ? IDS_WIN10_WELCOME_HEADER
                               : IDS_WIN10_WELCOME_HEADER_AFTER_FIRST_RUN;
   html_source->AddLocalizedString("headerText", welcome_header_id);
 
@@ skipping 31 matching lines @@
   static const char kCssFilePath[] = "welcome.css";
   static const char kJsFilePath[] = "welcome.js";
 
   web_ui->AddMessageHandler(new WelcomeWin10Handler());
 
   content::WebUIDataSource* html_source =
       content::WebUIDataSource::Create(url.host());
 
   // Determine which variation to show.
   bool is_first_run = !UrlContainsKeyValueInQuery(url, "text", "faster");
-  bool is_inline_style = UrlContainsKeyValueInQuery(url, "style", "inline");
+  bool is_inline_style = ShouldShouldInlineStyleVariant(url);
 
   AddLocalizedStrings(html_source, is_first_run);
 
   if (is_inline_style) {
     html_source->AddResourcePath(kCssFilePath, IDR_WELCOME_WIN10_INLINE_CSS);
     html_source->AddResourcePath(kJsFilePath, IDR_WELCOME_WIN10_INLINE_JS);
     html_source->SetDefaultResource(IDR_WELCOME_WIN10_INLINE_HTML);
   } else {
     html_source->AddResourcePath(kCssFilePath, IDR_WELCOME_WIN10_SECTIONED_CSS);
     html_source->AddResourcePath(kJsFilePath, IDR_WELCOME_WIN10_SECTIONED_JS);
     html_source->SetDefaultResource(IDR_WELCOME_WIN10_SECTIONED_HTML);
   }
 
   // Logo images of all scales.
   html_source->AddResourcePath("logo-small.png", IDR_PRODUCT_LOGO_32);
   html_source->AddResourcePath("logo-small2x.png", IDR_PRODUCT_LOGO_64);
   html_source->AddResourcePath("logo-large.png", IDR_PRODUCT_LOGO_64);
   html_source->AddResourcePath("logo-large2x.png", IDR_PRODUCT_LOGO_128);
 
   content::WebUIDataSource::Add(Profile::FromWebUI(web_ui), html_source);
 }
 
 WelcomeWin10UI::~WelcomeWin10UI() = default;