DO NOT COMMIT: hack hack hacking on preloading md-settings

chrome/browser/ui/webui/settings/md_settings_ui.cc

Index: chrome/browser/ui/webui/settings/md_settings_ui.cc
diff --git a/chrome/browser/ui/webui/settings/md_settings_ui.cc b/chrome/browser/ui/webui/settings/md_settings_ui.cc
index 6e30deb2b5c5ed387ff911bb5cb9a4026e44fe40..4e0581289d4b152d1c67cf5b5bf55e5d368feb6d 100644
--- a/chrome/browser/ui/webui/settings/md_settings_ui.cc
+++ b/chrome/browser/ui/webui/settings/md_settings_ui.cc
@@ -6,9 +6,14 @@
 
 #include <stddef.h>
 
-#include <string>
+#include <vector>
 
+#include "base/bind.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/strings/string_piece.h"
+#include "base/strings/string_split.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/settings/about_handler.h"
 #include "chrome/browser/ui/webui/settings/appearance_handler.h"
@@ -32,9 +37,13 @@
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_ui.h"
-#include "content/public/browser/web_ui_data_source.h"
+
+// TODO(dbeam): make content/public interface for this.
+#include "content/browser/webui/shared_resources_data_source.h"
+
 #include "grit/settings_resources.h"
 #include "grit/settings_resources_map.h"
+#include "ui/base/resource/resource_bundle.h"
 
 #if defined(OS_CHROMEOS)
 #include "ash/common/system/chromeos/palette/palette_utils.h"
@@ -58,11 +67,15 @@
 #include "chrome/browser/ui/webui/settings/native_certificates_handler.h"
 #endif  // defined(USE_NSS_CERTS)
 
+#include "third_party/re2/src/re2/re2.h"
+
 namespace settings {
 
 MdSettingsUI::MdSettingsUI(content::WebUI* web_ui, const GURL& url)
     : content::WebUIController(web_ui),
-      WebContentsObserver(web_ui->GetWebContents()) {
+      WebContentsObserver(web_ui->GetWebContents()),
+      html_source_(nullptr) {
+      // weak_ptr_factory_(this) {
   Profile* profile = Profile::FromWebUI(web_ui);
   AddSettingsPageUIHandler(new AppearanceHandler(web_ui));
 
@@ -108,40 +121,154 @@ MdSettingsUI::MdSettingsUI(content::WebUI* web_ui, const GURL& url)
   CHECK(url.GetOrigin() == GURL(chrome::kChromeUISettingsURL).GetOrigin() ||
         url.GetOrigin() == GURL(chrome::kChromeUIMdSettingsURL).GetOrigin());
 
-  content::WebUIDataSource* html_source =
-      content::WebUIDataSource::Create(url.host());
+  html_source_ = content::WebUIDataSource::Create(url.host());
+  html_source_->SetRequestFilter(
+      base::Bind(&MdSettingsUI::RequestFilter, base::Unretained(this)));
 
 #if defined(OS_CHROMEOS)
   chromeos::settings::EasyUnlockSettingsHandler* easy_unlock_handler =
-      chromeos::settings::EasyUnlockSettingsHandler::Create(html_source,
+      chromeos::settings::EasyUnlockSettingsHandler::Create(html_source_,
                                                             profile);
   if (easy_unlock_handler)
     AddSettingsPageUIHandler(easy_unlock_handler);
 
-  html_source->AddBoolean("noteAllowed", ash::IsPaletteEnabled());
-  html_source->AddBoolean("quickUnlockEnabled",
-                          chromeos::IsQuickUnlockEnabled());
+  html_source_->AddBoolean("noteAllowed", ash::IsPaletteEnabled());
+  html_source_->AddBoolean("quickUnlockEnabled",
+                           chromeos::IsQuickUnlockEnabled());
 #endif
 
-  AddSettingsPageUIHandler(AboutHandler::Create(html_source, profile));
-  AddSettingsPageUIHandler(ResetSettingsHandler::Create(html_source, profile));
+  AddSettingsPageUIHandler(AboutHandler::Create(html_source_, profile));
+  AddSettingsPageUIHandler(ResetSettingsHandler::Create(html_source_, profile));
 
   // Add all settings resources.
   for (size_t i = 0; i < kSettingsResourcesSize; ++i) {
-    html_source->AddResourcePath(kSettingsResources[i].name,
-                                 kSettingsResources[i].value);
+    html_source_->AddResourcePath(kSettingsResources[i].name,
+                                  kSettingsResources[i].value);
   }
 
-  AddLocalizedStrings(html_source, profile);
-  html_source->SetDefaultResource(IDR_SETTINGS_SETTINGS_HTML);
+  AddLocalizedStrings(html_source_, profile);
+  html_source_->SetDefaultResource(IDR_SETTINGS_SETTINGS_HTML);
+
+  base::TimeTicks then = base::TimeTicks::Now();
+
+  std::vector<GURL> urls;
+  GatherPreloadUrls(GURL("chrome://md-settings/settings.html"), &urls);
+
+  for (const GURL& url : urls) {
+    const std::string spec = url.spec();
+
+    std::string rel;
+    std::string as;
+    if (base::EndsWith(spec, ".js", base::CompareCase::INSENSITIVE_ASCII)) {
+      rel = "preload";
+      as = " as=\"script\"";
+    } else if (base::EndsWith(spec, ".css",
+                              base::CompareCase::INSENSITIVE_ASCII)) {
+      rel = "preload";
+      as = " as=\"style\"";
+    } else if (base::EndsWith(spec, ".html",
+                              base::CompareCase::INSENSITIVE_ASCII)) {
+      continue;
+      rel = "import";
+      // as="document" doesn't work yet.
+    }
+
+    preloads_.append(base::StringPrintf(
+        "<link rel=\"%s\" href=\"%s\"%s>\n",
+        rel.c_str(), spec.c_str(), as.c_str()));
+  }
+
+  LOG(ERROR) << "time gathering: " << (base::TimeTicks::Now() - then).InMilliseconds();
 
   content::WebUIDataSource::Add(web_ui->GetWebContents()->GetBrowserContext(),
-                                html_source);
+                                html_source_);
 }
 
 MdSettingsUI::~MdSettingsUI() {
 }
 
+bool MdSettingsUI::RequestFilter(
+    const std::string& path,
+    const content::WebUIDataSource::GotDataCallback& callback) {
+  if (!path.empty())
+    return false;
+
+  base::StringPiece settings_html =
+      ui::ResourceBundle::GetSharedInstance().GetRawDataResource(
+          IDR_SETTINGS_SETTINGS_HTML);
+  
+  std::string preloads_placeholder("<!-- preloads -->");
+  size_t preloads_start = settings_html.find(preloads_placeholder);
+
+  std::string response;
+  settings_html.substr(0, preloads_start).AppendToString(&response);
+  response.append(preloads_);
+  settings_html.substr(preloads_start + preloads_placeholder.size())
+      .AppendToString(&response);
+
+  callback.Run(base::RefCountedString::TakeString(&response));
+  return true;
+}
+
+void MdSettingsUI::GatherPreloadUrls(const GURL& url, std::vector<GURL>* urls) {
+  CHECK(url.SchemeIs(content::kChromeUIScheme) &&
+        (url.host() == content::kChromeUIResourcesHost ||
+         url.host() == chrome::kChromeUISettingsHost ||
+         url.host() == chrome::kChromeUIMdSettingsHost));
+
+  std::string path = url.path();
+  CHECK(!path.empty());
+
+  if (path[0] == '/')
+    path.erase(0, 1);
+
+  int idr = -1;
+
+  if (url.host() == content::kChromeUIResourcesHost) {
+    const auto& map = content::SharedResourcesDataSource::GetResourcesMap();
+    auto it = map.find(path);
+    if (it != map.end())
+      idr = it->second;
+  } else {
+    const auto& map = html_source_->path_to_idr_map();
+    auto it = map.find(path);
+    if (it != map.end())
+      idr = it->second;
+  }
+
+  if (idr == -1) {
+    LOG(ERROR) << "@@ unknown url: " << url << ", path: " << path << " @@";
+    return;
+  }
+
+  std::string resource = ui::ResourceBundle::GetSharedInstance()
+      .GetRawDataResource(idr).as_string();
+
+  re2::StringPiece re2_resource(resource);
+
+  re2::RE2 regex(
+      "<link[^>]+?rel=\"import\"[^>]+?href=\"([^\"]+)\"|"
+      "<link[^>]+?rel=\"stylesheet\"[^>]+?href=\"([^\"]+)\"|"
+      "<script[^>]+?src=\"([^\"]+)");
+
+  re2::StringPiece html, css, js;
+
+  while (re2::RE2::FindAndConsume(&re2_resource, regex, &html, &css, &js)) {
+    CHECK_EQ(html.empty() + css.empty() + js.empty(), 2);
+
+    std::string new_path = html.as_string() + css.as_string() + js.as_string();
+    CHECK(!new_path.empty());
+
+    GURL new_url = url.Resolve(new_path);
+
+    if (std::find(urls->begin(), urls->end(), new_url) != urls->end())
+      continue;
+
+    urls->push_back(new_url);
+    GatherPreloadUrls(new_url, urls);
+  }
+}
+
 void MdSettingsUI::AddSettingsPageUIHandler(SettingsPageUIHandler* handler) {
   DCHECK(handler);
   handlers_.insert(handler);