Introduce ChromeZoomLevelPref, make zoom level prefs independent of profile prefs.

chrome/browser/ui/zoom/chrome_zoom_level_prefs.cc

+// Copyright (c) 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 "chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
+
+#include <sstream>
+
+#include "base/bind.h"
+#include "base/prefs/json_pref_store.h"
+#include "base/prefs/pref_filter.h"
+#include "base/prefs/pref_registry_simple.h"
+#include "base/prefs/pref_service_factory.h"
+#include "base/prefs/scoped_user_pref_update.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/values.h"
+#include "chrome/common/chrome_constants.h"
+#include "chrome/common/pref_names.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/host_zoom_map.h"
+#include "content/public/common/page_zoom.h"
+
+namespace chrome {
+
+ChromeZoomLevelPrefs::ChromeZoomLevelPrefs(PrefService* pref_service,
+                                           const base::FilePath& profile_path)
+    : pref_service_(pref_service),
+      profile_path_(profile_path),
+      host_zoom_map_(NULL) {
+  DCHECK(pref_service_);
+}
+
+ChromeZoomLevelPrefs::~ChromeZoomLevelPrefs() {
+  zoom_subscription_.reset();

[gab, 2014/10/02 20:58:42]

Why explicitly reset it? Doesn't letting it go out of scope naturally do the
right thing implicitly?

[wjmaclean, 2014/10/03 18:53:22]

You're right ... there may once have been a reason for this, but it's certainly
gone now.

+}
+
+void ChromeZoomLevelPrefs::InitPrefsAndCopyToHostZoomMap(
+    const base::FilePath& partition_path,
+    content::HostZoomMap* host_zoom_map) {
+  DCHECK(!partition_path.empty());
+  DCHECK((partition_path == profile_path_) ||

[gab, 2014/10/02 20:58:42]

Remove unnecessary surrounding ()

[wjmaclean, 2014/10/03 18:53:22]

Done.

+         profile_path_.IsParent(partition_path));
+  DCHECK(host_zoom_map);
+  host_zoom_map_ = host_zoom_map;

[gab, 2014/10/02 20:58:42]

DCHECK(!host_zoom_map_);
? (to make sure Init is only called once)

[wjmaclean, 2014/10/03 18:53:22]

Done.

+
+  // Create a partition_key string with no '.'s in it. For the default
+  // StoragePartition, this string will always be "0".
+  base::FilePath partition_relative_path;
+  profile_path_.AppendRelativePath(partition_path, &partition_relative_path);
+  size_t int_key =
+#if defined(COMPILER_MSVC)
+      BASE_HASH_NAMESPACE::hash_value(partition_relative_path);
+#else
+      BASE_HASH_NAMESPACE::hash<base::FilePath>()(partition_relative_path);
+#endif  // COMPILER
+  partition_key_ = base::IntToString(int_key);
+
+  // Initialize the default zoom level.
+  host_zoom_map_->SetDefaultZoomLevel(GetDefaultZoomLevelPref());
+
+  // Initialize the HostZoomMap with per-host zoom levels from the persisted
+  // zoom-level preference values.
+  const base::DictionaryValue* host_zoom_dictionaries =
+      pref_service_->GetDictionary(prefs::kPerHostZoomLevels);

[gab, 2014/10/02 20:58:42]

I'm confused, so you migrate things out of kProfilePerHostZoomLevels into
another pref (kPerHostZoomLevels) in the same PrefService??

[wjmaclean, 2014/10/03 18:53:22]

Yes, although it's a little more than that.

Prior to this CL, there was (for example), only a single default zoom level
stored in prefs. Now every storage partition will have one (outside the scope of
this CL), and all the default zoom levels are stored in a Dictionary in the main
prefs (I would rather have had a separate PrefService for the individual
StoragePartitions, but bauerb@ felt that would incur too much additional
overhead).

Similarly, prior to this CL we had a single Dictionary storing per-host zoom
levels for everyone. After, we will have the capability to store separate
per-host zoom levels for each StoragePartition (in a follow-on CL we migrate
ownership of this class out of ProfileImpl and into StoragePartition).

+  const base::DictionaryValue* host_zoom_dictionary;
+  if (host_zoom_dictionaries &&
+      host_zoom_dictionaries->GetDictionary(partition_key_,
+                                            &host_zoom_dictionary)) {
+    std::vector<std::string> keys_to_remove;
+    for (base::DictionaryValue::Iterator i(*host_zoom_dictionary); !i.IsAtEnd();
+         i.Advance()) {
+      const std::string& host(i.key());
+      double zoom_level = 0;
+
+      bool success = i.value().GetAsDouble(&zoom_level);
+      DCHECK(success);
+
+      if (host.empty() ||
+          content::ZoomValuesEqual(zoom_level,
+                                   host_zoom_map_->GetDefaultZoomLevel())) {
+        keys_to_remove.push_back(host);
+        continue;
+      }
+
+      host_zoom_map_->SetZoomLevelForHost(host, zoom_level);
+    }
+
+    // Sanitize prefs to remove entries that match the default zoom level and/or
+    // have an empty host.
+    {
+      DictionaryPrefUpdate update(pref_service_, prefs::kPerHostZoomLevels);
+      base::DictionaryValue* host_zoom_dictionaries = update.Get();
+      base::DictionaryValue* host_zoom_dictionary;
+      if (!host_zoom_dictionaries->GetDictionary(partition_key_,
+                                                 &host_zoom_dictionary)) {
+        host_zoom_dictionary = new base::DictionaryValue();
+        host_zoom_dictionaries->Set(partition_key_, host_zoom_dictionary);
+      }
+
+      for (std::vector<std::string>::const_iterator it = keys_to_remove.begin();
+           it != keys_to_remove.end();
+           ++it) {
+        host_zoom_dictionary->RemoveWithoutPathExpansion(*it, NULL);
+      }
+    }
+  }
+  zoom_subscription_ = host_zoom_map_->AddZoomLevelChangedCallback(base::Bind(
+      &ChromeZoomLevelPrefs::OnZoomLevelChanged, base::Unretained(this)));
+}
+
+void ChromeZoomLevelPrefs::SetDefaultZoomLevelPref(double level) {
+  if (host_zoom_map_->GetDefaultZoomLevel() == level)
+    return;
+
+  DictionaryPrefUpdate update(pref_service_, prefs::kDefaultZoomLevel);
+  update->SetDouble(partition_key_, level);
+  // For unregistered paths, OnDefaultZoomLevelChanged won't be called, so
+  // set this manually.
+  host_zoom_map_->SetDefaultZoomLevel(level);
+  default_zoom_changed_callbacks_.Notify();
+}
+
+double ChromeZoomLevelPrefs::GetDefaultZoomLevelPref() {
+  double default_zoom_level = 0.0;
+
+  const base::DictionaryValue* default_zoom_level_dictionary =
+      pref_service_->GetDictionary(prefs::kDefaultZoomLevel);
+  if (!default_zoom_level_dictionary ||

[gab, 2014/10/02 20:58:42]

PrefService::GetDictionary() never returns NULL.

[wjmaclean, 2014/10/03 18:53:22]

Done.

+      !default_zoom_level_dictionary->GetDouble(partition_key_,
+                                                &default_zoom_level)) {
+    // We will only get here if the default zoom level for this partition
+    // has never been set before.
+    SetDefaultZoomLevelPref(default_zoom_level);
+  }
+  return default_zoom_level;
+}
+
+scoped_ptr<ChromeZoomLevelPrefs::DefaultZoomLevelSubscription>
+ChromeZoomLevelPrefs::RegisterDefaultZoomLevelCallback(
+    const base::Closure& callback) {
+  return default_zoom_changed_callbacks_.Add(callback);
+}
+
+void ChromeZoomLevelPrefs::OnZoomLevelChanged(
+    const content::HostZoomMap::ZoomLevelChange& change) {
+  if (change.mode != content::HostZoomMap::ZOOM_CHANGED_FOR_HOST)
+    return;
+  double level = change.zoom_level;
+  // Note: the following will create the dictionary if it doesn't already exist.
+  DictionaryPrefUpdate update(pref_service_, prefs::kPerHostZoomLevels);
+  base::DictionaryValue* host_zoom_dictionaries = update.Get();
+  DCHECK(host_zoom_dictionaries);
+
+  base::DictionaryValue* host_zoom_dictionary;
+  if (!host_zoom_dictionaries->GetDictionary(partition_key_,
+                                             &host_zoom_dictionary)) {
+    host_zoom_dictionary = new base::DictionaryValue();
+    host_zoom_dictionaries->Set(partition_key_, host_zoom_dictionary);
+  }
+
+  if (content::ZoomValuesEqual(level, host_zoom_map_->GetDefaultZoomLevel()))
+    host_zoom_dictionary->RemoveWithoutPathExpansion(change.host, NULL);
+  else
+    host_zoom_dictionary->SetDoubleWithoutPathExpansion(change.host, level);
+}
+
+}  // namespace chrome