Get rid of user-level styles.

chrome/browser/user_style_sheet_watcher.cc

-// Copyright (c) 2012 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/bind.h"
-#include "base/file_util.h"
-#include "chrome/browser/profiles/profile.h"
-#include "content/public/browser/notification_service.h"
-#include "content/public/browser/notification_types.h"
-#include "content/public/browser/web_contents.h"
-
-using ::base::FilePathWatcher;
-using content::BrowserThread;
-using content::WebContents;
-
-namespace {
-
-// The subdirectory of the profile that contains the style sheet.
-const char kStyleSheetDir[] = "User StyleSheets";
-// The filename of the stylesheet.
-const char kUserStyleSheetFile[] = "Custom.css";
-
-}  // namespace
-
-// UserStyleSheetLoader is responsible for loading  the user style sheet on the
-// file thread and sends a notification when the style sheet is loaded. It is
-// a helper to UserStyleSheetWatcher. The reference graph is as follows:
-//
-// .-----------------------.    owns    .-----------------.
-// | UserStyleSheetWatcher |----------->| FilePathWatcher |
-// '-----------------------'            '-----------------'
-//             |                                 |
-//             V                                 |
-//  .----------------------.                     |
-//  | UserStyleSheetLoader |<--------------------'
-//  '----------------------'
-//
-// FilePathWatcher's reference to UserStyleSheetLoader is used for delivering
-// the change notifications. Since they happen asynchronously,
-// UserStyleSheetWatcher and its FilePathWatcher may be destroyed while a
-// callback to UserStyleSheetLoader is in progress, in which case the
-// UserStyleSheetLoader object outlives the watchers.
-class UserStyleSheetLoader
-    : public base::RefCountedThreadSafe<UserStyleSheetLoader> {
- public:
-  UserStyleSheetLoader();
-
-  GURL user_style_sheet() const {
-    return user_style_sheet_;
-  }
-
-  // Load the user style sheet on the file thread and convert it to a
-  // base64 URL.  Posts the base64 URL back to the UI thread.
-  void LoadStyleSheet(const base::FilePath& style_sheet_file);
-
-  // Register a callback to be called whenever the stylesheet gets updated.
-  scoped_ptr<base::CallbackList<void(void)>::Subscription>
-  RegisterOnStyleSheetUpdatedCallback(const base::Closure& callback);
-
-  // Send out a notification if the stylesheet has already been loaded.
-  void NotifyLoaded();
-
-  // FilePathWatcher::Callback method:
-  void NotifyPathChanged(const base::FilePath& path, bool error);
-
- private:
-  friend class base::RefCountedThreadSafe<UserStyleSheetLoader>;
-  ~UserStyleSheetLoader();
-
-  // Called on the UI thread after the stylesheet has loaded.
-  void SetStyleSheet(const GURL& url);
-
-  // The user style sheet as a base64 data:// URL.
-  GURL user_style_sheet_;
-
-  // Whether the stylesheet has been loaded.
-  bool has_loaded_;
-
-  base::CallbackList<void(void)> style_sheet_updated_callbacks_;
-
-  DISALLOW_COPY_AND_ASSIGN(UserStyleSheetLoader);
-};
-
-UserStyleSheetLoader::UserStyleSheetLoader()
-    : has_loaded_(false) {
-}
-
-UserStyleSheetLoader::~UserStyleSheetLoader() {
-}
-
-scoped_ptr<base::CallbackList<void(void)>::Subscription>
-UserStyleSheetLoader::RegisterOnStyleSheetUpdatedCallback(
-    const base::Closure& callback) {
-  return style_sheet_updated_callbacks_.Add(callback);
-}
-
-void UserStyleSheetLoader::NotifyLoaded() {
-  if (has_loaded_) {
-    style_sheet_updated_callbacks_.Notify();
-  }
-}
-
-void UserStyleSheetLoader::NotifyPathChanged(const base::FilePath& path,
-                                             bool error) {
-  if (!error)
-    LoadStyleSheet(path);
-}
-
-void UserStyleSheetLoader::LoadStyleSheet(
-    const base::FilePath& style_sheet_file) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  // We keep the user style sheet in a subdir so we can watch for changes
-  // to the file.
-  base::FilePath style_sheet_dir = style_sheet_file.DirName();
-  if (!base::DirectoryExists(style_sheet_dir)) {
-    if (!file_util::CreateDirectory(style_sheet_dir))
-      return;
-  }
-  // Create the file if it doesn't exist.
-  if (!base::PathExists(style_sheet_file))
-    file_util::WriteFile(style_sheet_file, "", 0);
-
-  std::string css;
-  bool rv = base::ReadFileToString(style_sheet_file, &css);
-  GURL style_sheet_url;
-  if (rv && !css.empty()) {
-    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);
-    }
-  }
-  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-                          base::Bind(&UserStyleSheetLoader::SetStyleSheet, this,
-                                     style_sheet_url));
-}
-
-void UserStyleSheetLoader::SetStyleSheet(const GURL& url) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  has_loaded_ = true;
-  user_style_sheet_ = url;
-  NotifyLoaded();
-}
-
-UserStyleSheetWatcher::UserStyleSheetWatcher(Profile* profile,
-                                             const base::FilePath& profile_path)
-    : RefcountedBrowserContextKeyedService(content::BrowserThread::UI),
-      profile_(profile),
-      profile_path_(profile_path),
-      loader_(new UserStyleSheetLoader) {
-  // 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,
-                 content::NOTIFICATION_WEB_CONTENTS_RENDER_VIEW_HOST_CREATED,
-                 content::NotificationService::AllBrowserContextsAndSources());
-}
-
-UserStyleSheetWatcher::~UserStyleSheetWatcher() {
-}
-
-void UserStyleSheetWatcher::Init() {
-  // Make sure we run on the file thread.
-  if (!BrowserThread::CurrentlyOn(BrowserThread::FILE)) {
-    BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-                            base::Bind(&UserStyleSheetWatcher::Init, this));
-    return;
-  }
-
-  if (!file_watcher_.get()) {
-    file_watcher_.reset(new FilePathWatcher);
-    base::FilePath style_sheet_file = profile_path_.AppendASCII(kStyleSheetDir)
-                                             .AppendASCII(kUserStyleSheetFile);
-    if (!file_watcher_->Watch(
-            style_sheet_file,
-            false,
-            base::Bind(&UserStyleSheetLoader::NotifyPathChanged,
-                       loader_.get()))) {
-      LOG(ERROR) << "Failed to setup watch for " << style_sheet_file.value();
-    }
-    loader_->LoadStyleSheet(style_sheet_file);
-  }
-}
-
-GURL UserStyleSheetWatcher::user_style_sheet() const {
-  return loader_->user_style_sheet();
-}
-
-scoped_ptr<base::CallbackList<void(void)>::Subscription>
-UserStyleSheetWatcher::RegisterOnStyleSheetUpdatedCallback(
-    const base::Closure& callback) {
-  return loader_->RegisterOnStyleSheetUpdatedCallback(callback);
-}
-
-void UserStyleSheetWatcher::Observe(int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK(type == content::NOTIFICATION_WEB_CONTENTS_RENDER_VIEW_HOST_CREATED);
-  if (profile_->IsSameProfile(Profile::FromBrowserContext(
-          content::Source<WebContents>(source)->GetBrowserContext()))) {
-    loader_->NotifyLoaded();
-    registrar_.RemoveAll();
-  }
-}
-
-void UserStyleSheetWatcher::ShutdownOnUIThread() {
-  registrar_.RemoveAll();
-}