chrome/browser/ui/webui/theme_source.cc

// Copyright 2012 The Chromium Authors
// 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/theme_source.h"

#include <algorithm>
#include <string_view>

#include "base/functional/bind.h"
#include "base/memory/ref_counted_memory.h"
#include "base/metrics/histogram_functions.h"
#include "base/strings/strcat.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/timer/elapsed_timer.h"
#include "build/branding_buildflags.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/resources_util.h"
#include "chrome/browser/search/instant_service.h"
#include "chrome/browser/themes/browser_theme_pack.h"
#include "chrome/browser/themes/theme_properties.h"
#include "chrome/browser/themes/theme_service.h"
#include "chrome/browser/themes/theme_service_factory.h"
#include "chrome/browser/ui/color/chrome_color_id.h"
#include "chrome/browser/ui/color/chrome_color_provider_utils.h"
#include "chrome/browser/ui/webui/current_channel_logo.h"
#include "chrome/browser/ui/webui/ntp/ntp_resource_cache.h"
#include "chrome/browser/ui/webui/ntp/ntp_resource_cache_factory.h"
#include "chrome/common/channel_info.h"
#include "chrome/common/url_constants.h"
#include "chrome/grit/theme_resources.h"
#include "components/version_info/version_info.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/url_data_source.h"
#include "content/public/browser/web_contents.h"
#include "content/public/common/url_constants.h"
#include "net/base/url_util.h"
#include "services/network/public/mojom/content_security_policy.mojom.h"
#include "ui/base/resource/resource_bundle.h"
#include "ui/base/resource/resource_scale_factor.h"
#include "ui/base/webui/web_ui_util.h"
#include "ui/color/color_provider.h"
#include "ui/color/color_provider_utils.h"
#include "ui/gfx/codec/png_codec.h"
#include "ui/gfx/image/image_skia.h"
#include "ui/gfx/image/image_skia_rep.h"
#include "url/gurl.h"

#if BUILDFLAG(IS_CHROMEOS)
#include "chrome/grit/cros_styles_resources.h"  // nogncheck crbug.com/1113869
#include "ui/chromeos/styles/cros_tokens_color_mappings.h"
#endif  // BUILDFLAG(IS_CHROMEOS)

namespace {

GURL GetThemeUrl(const std::string& path) {
  return GURL(std::string(content::kChromeUIScheme) + "://" +
              std::string(chrome::kChromeUIThemeHost) + "/" + path);
}

bool IsNewTabCssPath(const std::string& path) {
  static const char kNewTabThemeCssPath[] = "css/new_tab_theme.css";
  static const char kIncognitoTabThemeCssPath[] = "css/incognito_tab_theme.css";
  return path == kNewTabThemeCssPath || path == kIncognitoTabThemeCssPath;
}

}  // namespace

////////////////////////////////////////////////////////////////////////////////
// ThemeSource, public:

// static
const char ThemeSource::kThemeColorsCssUrl[] =
    "chrome://theme/colors.css?sets=ui,chrome";

ThemeSource::ThemeSource(Profile* profile)
    : profile_(profile), serve_untrusted_(false) {}

ThemeSource::ThemeSource(Profile* profile, bool serve_untrusted)
    : profile_(profile), serve_untrusted_(serve_untrusted) {}

ThemeSource::~ThemeSource() = default;

std::string ThemeSource::GetSource() {
  return serve_untrusted_ ? chrome::kChromeUIUntrustedThemeURL
                          : chrome::kChromeUIThemeHost;
}

void ThemeSource::StartDataRequest(
    const GURL& url,
    const content::WebContents::Getter& wc_getter,
    content::URLDataSource::GotDataCallback callback) {
  // TODO(crbug.com/40050262): Simplify usages of |path| since |url| is
  // available.
  const std::string path = content::URLDataSource::URLToRequestPath(url);
  // Default scale factor if not specified.
  float scale = 1.0f;
  // All frames by default if not specified.
  int frame = -1;
  std::string parsed_path;
  webui::ParsePathAndImageSpec(GetThemeUrl(path), &parsed_path, &scale, &frame);

  if (IsNewTabCssPath(parsed_path)) {
    DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
    NTPResourceCache::WindowType type =
        NTPResourceCache::GetWindowType(profile_);
    NTPResourceCache* cache = NTPResourceCacheFactory::GetForProfile(profile_);
    std::move(callback).Run(cache->GetNewTabCSS(type, wc_getter));
    return;
  }

  // kColorsCssPath should stay consistent with COLORS_CSS_SELECTOR in
  // colors_css_updater.js.
  constexpr char kColorsCssPath[] = "colors.css";
  if (parsed_path == kColorsCssPath) {
    SendColorsCss(url, wc_getter, std::move(callback));
    return;
  }

#if BUILDFLAG(IS_CHROMEOS)
  constexpr char kTypographyCssPath[] = "typography.css";
  if (parsed_path == kTypographyCssPath) {
    SendTypographyCss(std::move(callback));
    return;
  }
#endif

  int resource_id = -1;
  if (parsed_path == "current-channel-logo") {
    resource_id = webui::CurrentChannelLogoResourceId();
  } else {
    resource_id = ResourcesUtil::GetThemeResourceId(parsed_path);
  }

  // Limit the maximum scale we'll respond to.  Very large scale factors can
  // take significant time to serve or, at worst, crash the browser due to OOM.
  // We don't want to clamp to the max scale factor, though, for devices that
  // use 2x scale without 2x data packs, as well as omnibox requests for larger
  // (but still reasonable) scales (see below).
  const float max_scale = ui::GetScaleForResourceScaleFactor(
      ui::ResourceBundle::GetSharedInstance().GetMaxResourceScaleFactor());
  const float unreasonable_scale = max_scale * 32;
  // TODO(reveman): Add support frames beyond 0 (crbug.com/750064).
  if ((resource_id == -1) || (scale >= unreasonable_scale) || (frame > 0)) {
    // Either we have no data to send back, or the requested scale is
    // unreasonably large.  This shouldn't happen normally, as chrome://theme/
    // URLs are only used by WebUI pages and component extensions.  However, the
    // user can also enter these into the omnibox, so we need to fail
    // gracefully.
    std::move(callback).Run(nullptr);
  } else if ((GetMimeType(url) == "image/png") &&
             ((scale > max_scale) || (frame != -1))) {
    // This will extract and scale frame 0 of animated images.
    // TODO(reveman): Support scaling of animated images and avoid scaling and
    // re-encode when specific frame is specified (crbug.com/750064).
    DCHECK_LE(frame, 0);
    SendThemeImage(std::move(callback), resource_id, scale);
  } else {
    SendThemeBitmap(std::move(callback), resource_id, scale);
  }
}

std::string ThemeSource::GetMimeType(const GURL& url) {
  const std::string_view file_path = url.path();

  if (base::EndsWith(file_path, ".css", base::CompareCase::INSENSITIVE_ASCII)) {
    return "text/css";
  }

  return "image/png";
}

bool ThemeSource::AllowCaching() {
  return false;
}

bool ThemeSource::ShouldServiceRequest(const GURL& url,
                                       content::BrowserContext* browser_context,
                                       int render_process_id) {
  return url.SchemeIs(chrome::kChromeSearchScheme)
             ? InstantService::ShouldServiceRequest(url, browser_context,
                                                    render_process_id)
             : URLDataSource::ShouldServiceRequest(url, browser_context,
                                                   render_process_id);
}

////////////////////////////////////////////////////////////////////////////////
// ThemeSource, private:

void ThemeSource::SendThemeBitmap(
    content::URLDataSource::GotDataCallback callback,
    int resource_id,
    float scale) {
  ui::ResourceScaleFactor scale_factor =
      ui::GetSupportedResourceScaleFactor(scale);
  if (BrowserThemePack::IsPersistentImageID(resource_id)) {
    scoped_refptr<base::RefCountedMemory> image_data(
        ThemeService::GetThemeProviderForProfile(profile_->GetOriginalProfile())
            .GetRawData(resource_id, scale_factor));
    std::move(callback).Run(image_data.get());
  } else {
    const ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
    std::move(callback).Run(
        rb.LoadDataResourceBytesForScale(resource_id, scale_factor));
  }
}

void ThemeSource::SendThemeImage(
    content::URLDataSource::GotDataCallback callback,
    int resource_id,
    float scale) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

  gfx::ImageSkia* image;
  if (BrowserThemePack::IsPersistentImageID(resource_id)) {
    const ui::ThemeProvider& tp = ThemeService::GetThemeProviderForProfile(
        profile_->GetOriginalProfile());
    image = tp.GetImageSkiaNamed(resource_id);
  } else {
    image =
        ui::ResourceBundle::GetSharedInstance().GetImageSkiaNamed(resource_id);
  }

  const gfx::ImageSkiaRep& rep = image->GetRepresentation(scale);
  std::optional<std::vector<uint8_t>> result =
      gfx::PNGCodec::EncodeBGRASkBitmap(rep.GetBitmap(),
                                        /*discard_transparency=*/false);
  if (result) {
    std::move(callback).Run(
        base::MakeRefCounted<base::RefCountedBytes>(std::move(result.value())));
  } else {
    std::move(callback).Run(base::MakeRefCounted<base::RefCountedBytes>());
  }
}

// static
std::optional<std::string> ThemeSource::GenerateColorsCss(
    const ui::ColorProvider& color_provider,
    const GURL& url,
    bool is_grayscale,
    bool is_baseline) {
  auto get_bool_param = [&](std::string_view key) {
    std::string value;
    return net::GetValueForKeyInQuery(url, key, &value) &&
           base::ToLowerASCII(value) == "true";
  };

  const bool generate_rgb_vars = get_bool_param("generate_rgb_vars");
  const bool shadow_host = get_bool_param("shadow_host");

  std::string sets_param;
  if (!net::GetValueForKeyInQuery(url, "sets", &sets_param)) {
    LOG(ERROR)
        << "colors.css requires a 'sets' query parameter to specify the color "
           "id sets returned e.g chrome://theme/colors.css?sets=ui,chrome";
    return std::nullopt;
  }

  std::vector<std::string_view> color_id_sets = base::SplitStringPiece(
      sets_param, ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);

  // Define the logic for each set. This allows us to validate input before
  // generating the CSS string.
  struct ColorSetDefinition {
    std::string_view name;
    ui::ColorId start;
    ui::ColorId end;
    // Callback converts ColorId to CSS variable name.
    base::RepeatingCallback<std::string(ui::ColorId)> name_mapper;
  };

  // Helper to adapt ui::ColorIdName to the CSS mapping callback format.
  auto to_css_id = [](std::string (*name_func)(ui::ColorId), ui::ColorId id) {
    return ui::ConvertColorProviderColorIdToCSSColorId(name_func(id));
  };

  const std::vector<ColorSetDefinition> definitions = {
      {"ui", ui::kUiColorsStart, ui::kUiColorsEnd,
       base::BindRepeating(to_css_id, ui::ColorIdName)},
      {"chrome", kChromeColorsStart, kChromeColorsEnd,
       base::BindRepeating(to_css_id, &ChromeColorIdName)},
#if BUILDFLAG(IS_CHROMEOS)
      {"ref", cros_tokens::kCrosRefColorsStart, cros_tokens::kCrosRefColorsEnd,
       base::BindRepeating(cros_tokens::ColorIdName)},
      {"sys", cros_tokens::kCrosSysColorsStart, cros_tokens::kCrosSysColorsEnd,
       base::BindRepeating(cros_tokens::ColorIdName)},
      {"legacy", cros_tokens::kLegacySemanticColorsStart,
       cros_tokens::kLegacySemanticColorsEnd,
       base::BindRepeating(cros_tokens::ColorIdName)},
#endif
  };

  // Validate only valid `color_id_sets` were requested.
  for (const auto& set_name : color_id_sets) {
    bool is_valid = std::ranges::any_of(
        definitions, [&](const auto& def) { return def.name == set_name; });
    if (!is_valid) {
      LOG(ERROR) << "Unrecognized color set specified: " << set_name;
      return std::nullopt;
    }
  }

  // Generate the CSS. Pre-calculate selector and theme info.
  std::string css_header;
  if (shadow_host) {
    css_header = ":host{";
  } else {
    css_header = "html:not(#z){";
  }

  if (is_grayscale) {
    base::StrAppend(&css_header, {"--user-color-source:baseline-grayscale;"});
  } else if (is_baseline) {
    base::StrAppend(&css_header, {"--user-color-source:baseline-default;"});
  }

  // Reserve memory to reduce reallocations. 75KB is a reasonable heuristic for
  // a full theme dump, minimizing string resizing during the loop.
  std::string css_string;
  css_string.reserve(75000);
  css_string.append(css_header);

  for (const auto& def : definitions) {
    if (!base::Contains(color_id_sets, def.name)) {
      continue;
    }

    for (ui::ColorId id = def.start; id < def.end; ++id) {
      const SkColor color = color_provider.GetColor(id);
      const std::string var_name = def.name_mapper.Run(id);
      const std::string color_str = ui::ConvertSkColorToCSSColor(color);

      // Format: --var-name: #RRGGBBAA;
      base::StrAppend(&css_string, {var_name, ":", color_str, ";"});

      if (generate_rgb_vars) {
        // Format: --var-name-rgb: R,G,B;
        const std::string rgb_str = color_utils::SkColorToRgbString(color);
        base::StrAppend(&css_string, {var_name, "-rgb:", rgb_str, ";"});
      }
    }
  }

  css_string.push_back('}');
  return css_string;
}

void ThemeSource::SendColorsCss(
    const GURL& url,
    const content::WebContents::Getter& wc_getter,
    content::URLDataSource::GotDataCallback callback) {
  base::ElapsedTimer timer;
  const ui::ColorProvider& color_provider = wc_getter.Run()->GetColorProvider();

  const auto* theme_service =
      ThemeServiceFactory::GetForProfile(profile_->GetOriginalProfile());

  std::optional<std::string> css_content =
      GenerateColorsCss(color_provider, url, theme_service->GetIsGrayscale(),
                        theme_service->GetIsBaseline());

  if (!css_content) {
    std::move(callback).Run(nullptr);
    return;
  }

  std::move(callback).Run(
      base::MakeRefCounted<base::RefCountedString>(std::move(*css_content)));

  // Measures the time it takes to generate the colors.css and queue it for the
  // renderer.
  UmaHistogramTimes("WebUI.ColorsStylesheetServingDuration", timer.Elapsed());
}

std::string ThemeSource::GetAccessControlAllowOriginForOrigin(
    const std::string& origin) {
  std::string allowed_origin_prefix = content::kChromeUIScheme;
  allowed_origin_prefix += "://";
  if (base::StartsWith(origin, allowed_origin_prefix,
                       base::CompareCase::SENSITIVE)) {
    return origin;
  }

  return content::URLDataSource::GetAccessControlAllowOriginForOrigin(origin);
}

#if BUILDFLAG(IS_CHROMEOS)
void ThemeSource::SendTypographyCss(
    content::URLDataSource::GotDataCallback callback) {
  const ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
  std::move(callback).Run(rb.LoadDataResourceBytesForScale(
      IDR_CROS_STYLES_UI_CHROMEOS_STYLES_CROS_TYPOGRAPHY_CSS,
      ui::kScaleFactorNone));
}
#endif

std::string ThemeSource::GetContentSecurityPolicy(
    network::mojom::CSPDirectiveName directive) {
  if (directive == network::mojom::CSPDirectiveName::DefaultSrc &&
      serve_untrusted_) {
    // TODO(crbug.com/40693568): Audit and tighten CSP.
    return std::string();
  }

  return content::URLDataSource::GetContentSecurityPolicy(directive);
}