Replace the index mapping of wallpaper picker UI and hard coded wallpaper index in C++

chrome/browser/ui/webui/options2/chromeos/wallpaper_thumbnails_source2.cc

+// Copyright (c) 2011 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/options2/chromeos/wallpaper_thumbnails_source2.h"
+
+#include "ash/desktop_background/desktop_background_resources.h"
+#include "base/memory/singleton.h"
+#include "base/string_number_conversions.h"
+#include "base/string_piece.h"
+#include "base/string_util.h"
+#include "base/stringprintf.h"
+#include "base/threading/thread_restrictions.h"
+#include "chrome/browser/io_thread.h"
+#include "chrome/browser/ui/webui/chrome_url_data_manager.h"
+#include "chrome/common/url_constants.h"
+#include "content/public/browser/browser_thread.h"
+#include "grit/ui_resources.h"
+#include "net/base/mime_util.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/gfx/codec/png_codec.h"
+
+namespace chromeos {
+namespace options2 {
+
+namespace {
+
+const char kDefaultWallpaperPrefix[] = "default_";
+
+int PathToIDR(const std::string& path) {
+  int idr = -1;
+  if (!StartsWithASCII(path, kDefaultWallpaperPrefix, false))
+    return idr;
+  int index;
+  if (base::StringToInt(base::StringPiece(path.begin() +

[flackr, 2012/04/18 20:16:34]

Should be able to use
if (base::StringToInt(path.substr(strlen(kDefaultWallpaperPrefix))))

[bshe, 2012/04/19 00:15:57]

It seems base::StringToInt only takes base::StringPiece argument type. So the
substr still need to implicitly convert to StringPiece anyway. And it seems
there are lots of places in the codebase use StringPiece this way. So probably
keep it this way also fine? Happy to change it if you dont think so.

On 2012/04/18 20:16:34, flackr wrote:

[flackr, 2012/04/19 20:13:07]

If this is an established pattern that's okay. It may be done for efficiency
purposes (i.e. a slice of the original rather than constructing a new string).

On 2012/04/19 00:15:57, bshe wrote:

+      strlen(kDefaultWallpaperPrefix), path.end()), &index))
+    idr = ash::GetWallpaperInfo(index).thumb_id;
+  return idr;
+}
+
+}  // namespace
+
+std::string GetDefaultWallpaperThumbnailURL(int index) {
+  return StringPrintf("%s%s%d", chrome::kChromeUIWallpaperThumbnailsURL,
+                      kDefaultWallpaperPrefix, index);
+}
+
+bool IsDefaultWallpaperURL(const std::string url, int* wallpaper_index) {

[flackr, 2012/04/18 20:16:34]

This seems very similar to the above method with slightly different inputs. You
should be able to at least factor out the getting the default wallpaper index
(if it is a default wallpaper) part.

[bshe, 2012/04/19 00:15:57]

Good point.

On 2012/04/18 20:16:34, flackr wrote:

+  DCHECK(wallpaper_index);
+  std::string prefix(chrome::kChromeUIWallpaperThumbnailsURL);
+  prefix += kDefaultWallpaperPrefix;
+  if (!StartsWithASCII(url, prefix, false))
+    return false;
+
+  int index = ash::GetInvalidWallpaperIndex();
+  if (base::StringToInt(base::StringPiece(url.begin() + prefix.length(),

[flackr, 2012/04/18 20:16:34]

You should be able to use:
if (base::StringToInt(url.substr(prefix.length()))

+                                          url.end()),
+                        &index)) {
+    *wallpaper_index = index;
+    return true;
+  }
+
+  return false;
+}
+
+WallpaperThumbnailsSource::WallpaperThumbnailsSource()
+    : DataSource(chrome::kChromeUIWallpaperThumbnailsHost, NULL) {
+}
+
+WallpaperThumbnailsSource::~WallpaperThumbnailsSource() {
+}
+
+void WallpaperThumbnailsSource::StartDataRequest(const std::string& path,
+                                                 bool is_incognito,
+                                                 int request_id) {
+  int idr = PathToIDR(path);
+  if (idr != -1) {
+    DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+    const ResourceBundle& rb = ResourceBundle::GetSharedInstance();
+    SendResponse(request_id, rb.LoadDataResourceBytes(idr));
+  }
+}
+
+std::string WallpaperThumbnailsSource::GetMimeType(const std::string&) const {
+  return "images/png";
+}
+
+}  // namespace options2
+}  // namespace chromeos