Add LogoTracker to fetch search providers' logos.

The LogoTracker keeps track of the logo for a search provider. The logo
is downloaded, cached on disk, and periodically revalidated.

This code lives inside a component (search_provider_logos) so it can be
used on both Android and iOS.

BUG=178922
NOTRY=true

Review URL: https://codereview.chromium.org/162373002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@267314 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 235 insertions, 0 deletions

diff --git a/components/search_provider_logos/logo_cache.cc b/components/search_provider_logos/logo_cache.cc
new file mode 100644
index 0000000..5858493
--- /dev/null
+++ b/components/search_provider_logos/logo_cache.cc
@@ -0,0 +1,235 @@
+// Copyright 2014 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/search_provider_logos/logo_cache.h"
+
+#include "base/file_util.h"
+#include "base/json/json_reader.h"
+#include "base/json/json_writer.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/values.h"
+
+namespace {
+
+// The cached logo metadata is persisted as JSON using these keys.
+const char kSourceUrlKey[] = "url";
+const char kExpirationTimeKey[] = "expiration_time";
+const char kCanShowAfterExpirationKey[] = "can_show_after_expiration";
+const char kFingerprintKey[] = "fingerprint";
+const char kOnClickURLKey[] = "on_click_url";
+const char kAltTextKey[] = "alt_text";
+const char kMimeTypeKey[] = "mime_type";
+const char kNumBytesKey[] = "num_bytes";
+
+bool GetTimeValue(const base::DictionaryValue& dict,
+                  const std::string& key,
+                  base::Time* time) {
+  std::string str;
+  int64 internal_time_value;
+  if (dict.GetString(key, &str) &&
+      base::StringToInt64(str, &internal_time_value)) {
+    *time = base::Time::FromInternalValue(internal_time_value);
+    return true;
+  }
+  return false;
+}
+
+void SetTimeValue(base::DictionaryValue& dict,
+                  const std::string& key,
+                  const base::Time& time) {
+  int64 internal_time_value = time.ToInternalValue();
+  dict.SetString(key, base::Int64ToString(internal_time_value));
+}
+
+}  // namespace
+
+namespace search_provider_logos {
+
+LogoCache::LogoCache(const base::FilePath& cache_directory)
+    : cache_directory_(cache_directory),
+      metadata_is_valid_(false) {
+  // The LogoCache can be constructed on any thread, as long as it's used
+  // on a single thread after construction.
+  thread_checker_.DetachFromThread();
+}
+
+LogoCache::~LogoCache() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+void LogoCache::UpdateCachedLogoMetadata(const LogoMetadata& metadata) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(metadata_);
+  DCHECK_EQ(metadata_->fingerprint, metadata.fingerprint);
+
+  UpdateMetadata(make_scoped_ptr(new LogoMetadata(metadata)));
+  WriteMetadata();
+}
+
+const LogoMetadata* LogoCache::GetCachedLogoMetadata() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  ReadMetadataIfNeeded();
+  return metadata_.get();
+}
+
+void LogoCache::SetCachedLogo(const EncodedLogo* logo) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  scoped_ptr<LogoMetadata> metadata;
+  if (logo) {
+    metadata.reset(new LogoMetadata(logo->metadata));
+    logo_num_bytes_ = static_cast<int>(logo->encoded_image->size());
+  }
+  UpdateMetadata(metadata.Pass());
+  WriteLogo(logo ? logo->encoded_image : NULL);
+}
+
+scoped_ptr<EncodedLogo> LogoCache::GetCachedLogo() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  ReadMetadataIfNeeded();
+  if (!metadata_)
+    return scoped_ptr<EncodedLogo>();
+
+  scoped_refptr<base::RefCountedString> encoded_image =
+      new base::RefCountedString();
+  if (!base::ReadFileToString(GetLogoPath(), &encoded_image->data())) {
+    UpdateMetadata(scoped_ptr<LogoMetadata>());
+    return scoped_ptr<EncodedLogo>();
+  }
+
+  if (encoded_image->size() != static_cast<size_t>(logo_num_bytes_)) {
+    // Delete corrupt metadata and logo.
+    DeleteLogoAndMetadata();
+    UpdateMetadata(scoped_ptr<LogoMetadata>());
+    return scoped_ptr<EncodedLogo>();
+  }
+
+  scoped_ptr<EncodedLogo> logo(new EncodedLogo());
+  logo->encoded_image = encoded_image;
+  logo->metadata = *metadata_;
+  return logo.Pass();
+}
+
+// static
+scoped_ptr<LogoMetadata> LogoCache::LogoMetadataFromString(
+    const std::string& str, int* logo_num_bytes) {
+  scoped_ptr<base::Value> value(base::JSONReader::Read(str));
+  base::DictionaryValue* dict;
+  if (!value || !value->GetAsDictionary(&dict))
+    return scoped_ptr<LogoMetadata>();
+
+  scoped_ptr<LogoMetadata> metadata(new LogoMetadata());
+  if (!dict->GetString(kSourceUrlKey, &metadata->source_url) ||
+      !dict->GetString(kFingerprintKey, &metadata->fingerprint) ||
+      !dict->GetString(kOnClickURLKey, &metadata->on_click_url) ||
+      !dict->GetString(kAltTextKey, &metadata->alt_text) ||
+      !dict->GetString(kMimeTypeKey, &metadata->mime_type) ||
+      !dict->GetBoolean(kCanShowAfterExpirationKey,
+                        &metadata->can_show_after_expiration) ||
+      !dict->GetInteger(kNumBytesKey, logo_num_bytes) ||
+      !GetTimeValue(*dict, kExpirationTimeKey, &metadata->expiration_time)) {
+    return scoped_ptr<LogoMetadata>();
+  }
+
+  return metadata.Pass();
+}
+
+// static
+void LogoCache::LogoMetadataToString(const LogoMetadata& metadata,
+                                     int num_bytes,
+                                     std::string* str) {
+  base::DictionaryValue dict;
+  dict.SetString(kSourceUrlKey, metadata.source_url);
+  dict.SetString(kFingerprintKey, metadata.fingerprint);
+  dict.SetString(kOnClickURLKey, metadata.on_click_url);
+  dict.SetString(kAltTextKey, metadata.alt_text);
+  dict.SetString(kMimeTypeKey, metadata.mime_type);
+  dict.SetBoolean(kCanShowAfterExpirationKey,
+                  metadata.can_show_after_expiration);
+  dict.SetInteger(kNumBytesKey, num_bytes);
+  SetTimeValue(dict, kExpirationTimeKey, metadata.expiration_time);
+  base::JSONWriter::Write(&dict, str);
+}
+
+base::FilePath LogoCache::GetLogoPath() {
+  return cache_directory_.Append(FILE_PATH_LITERAL("logo"));
+}
+
+base::FilePath LogoCache::GetMetadataPath() {
+  return cache_directory_.Append(FILE_PATH_LITERAL("metadata"));
+}
+
+void LogoCache::UpdateMetadata(scoped_ptr<LogoMetadata> metadata) {
+  metadata_ = metadata.Pass();
+  metadata_is_valid_ = true;
+}
+
+void LogoCache::ReadMetadataIfNeeded() {
+  if (metadata_is_valid_)
+    return;
+
+  scoped_ptr<LogoMetadata> metadata;
+  base::FilePath metadata_path = GetMetadataPath();
+  std::string str;
+  if (base::ReadFileToString(metadata_path, &str)) {
+    metadata = LogoMetadataFromString(str, &logo_num_bytes_);
+    if (!metadata) {
+      // Delete corrupt metadata and logo.
+      DeleteLogoAndMetadata();
+    }
+  }
+
+  UpdateMetadata(metadata.Pass());
+}
+
+void LogoCache::WriteMetadata() {
+  if (!EnsureCacheDirectoryExists())
+    return;
+
+  std::string str;
+  LogoMetadataToString(*metadata_, logo_num_bytes_, &str);
+  base::WriteFile(GetMetadataPath(), str.data(), static_cast<int>(str.size()));
+}
+
+void LogoCache::WriteLogo(scoped_refptr<base::RefCountedMemory> encoded_image) {
+  if (!EnsureCacheDirectoryExists())
+    return;
+
+  if (!metadata_ || !encoded_image) {
+    DeleteLogoAndMetadata();
+    return;
+  }
+
+  // To minimize the chances of ending up in an undetectably broken state:
+  // First, delete the metadata file, then update the logo file, then update the
+  // metadata file.
+  base::FilePath logo_path = GetLogoPath();
+  base::FilePath metadata_path = GetMetadataPath();
+
+  if (!base::DeleteFile(metadata_path, false))
+    return;
+
+  if (base::WriteFile(
+          logo_path,
+          encoded_image->front_as<char>(),
+          static_cast<int>(encoded_image->size())) == -1) {
+    base::DeleteFile(logo_path, false);
+    return;
+  }
+
+  WriteMetadata();
+}
+
+void LogoCache::DeleteLogoAndMetadata() {
+  base::DeleteFile(GetLogoPath(), false);
+  base::DeleteFile(GetMetadataPath(), false);
+}
+
+bool LogoCache::EnsureCacheDirectoryExists() {
+  if (base::DirectoryExists(cache_directory_))
+    return true;
+  return base::CreateDirectory(cache_directory_);
+}
+
+}  // namespace search_provider_logos