[ash-md] WIP Added wallpaper color caching.

components/wallpaper/pref_based_wallpaper_color_cache.cc

Index: components/wallpaper/pref_based_wallpaper_color_cache.cc
diff --git a/components/wallpaper/pref_based_wallpaper_color_cache.cc b/components/wallpaper/pref_based_wallpaper_color_cache.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4aad98564df080e8b411eb62ca42020026d4395b
--- /dev/null
+++ b/components/wallpaper/pref_based_wallpaper_color_cache.cc
@@ -0,0 +1,98 @@
+// Copyright 2017 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 "components/wallpaper/pref_based_wallpaper_color_cache.h"
+
+#include <memory>
+
+#include "base/memory/ptr_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
+#include "base/values.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
+#include "components/prefs/scoped_user_pref_update.h"
+#include "ui/gfx/color_utils.h"
+
+#include "base/logging.h"
+
+namespace wallpaper {
+
+const char kWallpaperCache[] = "wallpaper_cache";
+const char kWallpaperImagesNodeKey[] = "images";
+
+namespace {
+
+const char kColorNodeKey[] = "color";
+const char kLastAccessTimeNodeKey[] = "last_access_time";
+
+void UpdateAccessTime(base::DictionaryValue* images_dict, uint32_t image_id) {
+  const std::string key =
+      base::StringPrintf("%u.%s", image_id, kLastAccessTimeNodeKey);
+  images_dict->SetString(
+      key, base::Int64ToString(base::Time::Now().ToInternalValue()));
+}
+
+void UpdateColor(base::DictionaryValue* images_dict,
+                 uint32_t image_id,
+                 SkColor color) {
+  const std::string key = base::StringPrintf("%u.%s", image_id, kColorNodeKey);
+  images_dict->SetString(key, base::UintToString(color));
+}
+
+}  // namespace
+
+// static
+void PrefBasedWallpaperColorCache::RegisterPrefs(PrefRegistrySimple* registry) {
+  registry->RegisterDictionaryPref(kWallpaperCache);
+}
+
+PrefBasedWallpaperColorCache::PrefBasedWallpaperColorCache(
+    PrefService* pref_service)
+    : pref_service_(pref_service) {
+  CHECK(pref_service_);
+}
+
+PrefBasedWallpaperColorCache::~PrefBasedWallpaperColorCache() {}
+
+bool PrefBasedWallpaperColorCache::GetColor(uint32_t image_id,
+                                            SkColor* color) const {
+  const base::DictionaryValue* info_dict =
+      pref_service_->GetDictionary(kWallpaperCache);
+  LOG(ERROR) << *info_dict;
+
+  const std::string color_key = base::StringPrintf(
+      "%s.%u.%s", kWallpaperImagesNodeKey, image_id, kColorNodeKey);

[jonross, 2017/03/28 14:33:28]

This key seems more complex than is required.

Would not the image_id be sufficient?

+
+  // TODO(bruthig): Add UMA stat for hits/misses.
+  std::string color_str;
+  if (info_dict->GetString(color_key, &color_str)) {

[jonross, 2017/03/28 14:33:28]

You can store / extract integers directly as keys in DictionaryValue::SetInteger
/ GetInteger

+    CHECK(base::StringToUint(color_str, color));
+    return true;
+  }
+  return false;
+}
+
+void PrefBasedWallpaperColorCache::SetColor(uint32_t image_id, SkColor color) {
+  DictionaryPrefUpdate wallpaper_update(pref_service_, kWallpaperCache);
+  base::DictionaryValue* info_dict = wallpaper_update.Get();
+  if (!info_dict->HasKey(kWallpaperImagesNodeKey)) {
+    info_dict->Set(kWallpaperImagesNodeKey,
+                   base::MakeUnique<base::DictionaryValue>());
+  }
+  base::DictionaryValue* images_dict = nullptr;
+  info_dict->GetDictionary(kWallpaperImagesNodeKey, &images_dict);
+  UpdateColor(images_dict, image_id, color);
+  UpdateAccessTime(images_dict, image_id);
+
+  PurgeOldRecords();
+
+  LOG(ERROR) << *info_dict;
+}
+
+void PrefBasedWallpaperColorCache::PurgeOldRecords() {
+  // TODO(bruthig): Implement me!
+}
+
+}  // namespace wallpaper