First cut at custom user style sheets.

chrome/browser/user_style_sheet_watcher.cc

+// Copyright (c) 2010 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/user_style_sheet_watcher.h"
+
+#include "base/base64.h"
+#include "base/file_util.h"
+#include "chrome/common/notification_service.h"
+#include "chrome/common/notification_type.h"
+
+UserStyleSheetWatcher::UserStyleSheetWatcher(const FilePath& profile_path)
+    : profile_path_(profile_path),
+      has_loaded_(false) {
+  // Listen for when the first render view host is created.  If we load
+  // too fast, the first tab won't hear the notification and won't get
+  // the user style sheet.
+  registrar_.Add(this, NotificationType::RENDER_VIEW_HOST_CREATED_FOR_TAB,
+                 NotificationService::AllSources());
+}
+
+void UserStyleSheetWatcher::Observe(NotificationType type,
+    const NotificationSource& source, const NotificationDetails& details) {
+  DCHECK(type == NotificationType::RENDER_VIEW_HOST_CREATED_FOR_TAB);
+
+  if (has_loaded_) {
+    NotificationService::current()->Notify(
+        NotificationType::USER_STYLE_SHEET_UPDATED,
+        Source<UserStyleSheetWatcher>(this),
+        NotificationService::NoDetails());
+  }
+
+  registrar_.RemoveAll();
+}
+
+void UserStyleSheetWatcher::Init() {
+  ChromeThread::PostTask(ChromeThread::FILE, FROM_HERE,
+      NewRunnableMethod(this, &UserStyleSheetWatcher::LoadStyleSheet,
+                        profile_path_));
+}
+
+void UserStyleSheetWatcher::LoadStyleSheet(const FilePath& profile_path) {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::FILE));
+  // We keep the user style sheet in a subdir so we can watch for changes
+  // to the file.
+  FilePath style_sheet_dir = profile_path.AppendASCII("User StyleSheets");
+  if (!file_util::DirectoryExists(style_sheet_dir)) {
+    if (!file_util::CreateDirectory(style_sheet_dir))
+      return;
+  }
+  // Create the file if it doesn't exist.
+  FilePath css_file = style_sheet_dir.AppendASCII("Custom.css");
+  if (!file_util::PathExists(css_file))
+    file_util::WriteFile(css_file, "", 0);
+
+  std::string css;
+  bool rv = file_util::ReadFileToString(css_file, &css);
+  GURL style_sheet_url;
+  if (rv) {
+    std::string css_base64;
+    rv = base::Base64Encode(css, &css_base64);
+    if (rv) {
+      // WebKit knows about data urls, so convert the file to a data url.
+      const char kDataUrlPrefix[] = "data:text/css;charset=utf-8;base64,";
+      style_sheet_url = GURL(kDataUrlPrefix + css_base64);
+    }
+  }
+  ChromeThread::PostTask(ChromeThread::UI, FROM_HERE,
+      NewRunnableMethod(this, &UserStyleSheetWatcher::SetStyleSheet,
+                        style_sheet_url));
+}
+
+void UserStyleSheetWatcher::SetStyleSheet(const GURL& url) {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
+
+  has_loaded_ = true;
+  user_style_sheet_ = url;
+  NotificationService::current()->Notify(
+      NotificationType::USER_STYLE_SHEET_UPDATED,
+      Source<UserStyleSheetWatcher>(this),
+      NotificationService::NoDetails());
+}