Pref service: Add initial support for pref registration.

services/preferences/persistent_pref_store_impl.cc

 // 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 "services/preferences/persistent_pref_store_impl.h"
 
 #include <utility>
 
 #include "base/auto_reset.h"
 #include "base/memory/ptr_util.h"
+#include "base/stl_util.h"
 #include "base/values.h"
 #include "components/prefs/persistent_pref_store.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 namespace prefs {
 
 class PersistentPrefStoreImpl::Connection : public mojom::PersistentPrefStore {
  public:
   Connection(PersistentPrefStoreImpl* pref_store,
              mojom::PersistentPrefStoreRequest request,
-             mojom::PrefStoreObserverPtr observer)
+             mojom::PrefStoreObserverPtr observer,
+             ObservedPrefs observed_keys)
       : pref_store_(pref_store),
         binding_(this, std::move(request)),
-        observer_(std::move(observer)) {
+        observer_(std::move(observer)),
+        observed_keys_(std::move(observed_keys)) {
     auto error_callback =
         base::Bind(&PersistentPrefStoreImpl::Connection::OnConnectionError,
                    base::Unretained(this));
     binding_.set_connection_error_handler(error_callback);
     observer_.set_connection_error_handler(error_callback);
   }
 
   ~Connection() override = default;
 
   void OnPrefValueChanged(const std::string& key, const base::Value* value) {
-    if (write_in_progress_)
+    if (write_in_progress_ || !base::ContainsKey(observed_keys_, key))
       return;
 
     observer_->OnPrefChanged(key, value ? value->CreateDeepCopy() : nullptr);
   }
 
  private:
   // mojom::PersistentPrefStore:
   void SetValue(const std::string& key,
                 std::unique_ptr<base::Value> value,
                 uint32_t flags) override {
     base::AutoReset<bool> scoped_call_in_progress(&write_in_progress_, true);
     pref_store_->SetValue(key, std::move(value), flags);
   }
 
   void CommitPendingWrite() override { pref_store_->CommitPendingWrite(); }
   void SchedulePendingLossyWrites() override {
     pref_store_->SchedulePendingLossyWrites();
   }
   void ClearMutableValues() override { pref_store_->ClearMutableValues(); }
 
   void OnConnectionError() { pref_store_->OnConnectionError(this); }
 
   // Owns |this|.
-  PersistentPrefStoreImpl* pref_store_;
+  PersistentPrefStoreImpl* const pref_store_;
 
   mojo::Binding<mojom::PersistentPrefStore> binding_;
   mojom::PrefStoreObserverPtr observer_;
+  const ObservedPrefs observed_keys_;
 
   // If true then a write is in progress and any update notifications should be
   // ignored, as those updates would originate from ourselves.
   bool write_in_progress_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(Connection);
 };
 
 PersistentPrefStoreImpl::PersistentPrefStoreImpl(
     scoped_refptr<PersistentPrefStore> backing_pref_store,
     mojom::TrackedPreferenceValidationDelegatePtr validation_delegate,
     base::OnceClosure on_initialized)
     : backing_pref_store_(backing_pref_store),
       validation_delegate_(std::move(validation_delegate)) {
   backing_pref_store_->AddObserver(this);
   if (!backing_pref_store_->IsInitializationComplete()) {
     on_initialized_ = std::move(on_initialized);
     initializing_ = true;
     backing_pref_store_->ReadPrefsAsync(nullptr);
   }
 }
 
 PersistentPrefStoreImpl::~PersistentPrefStoreImpl() {
   backing_pref_store_->RemoveObserver(this);
 }
 
 mojom::PersistentPrefStoreConnectionPtr
-PersistentPrefStoreImpl::CreateConnection() {
+PersistentPrefStoreImpl::CreateConnection(ObservedPrefs observed_prefs) {
   DCHECK(!initializing_);
   if (!backing_pref_store_->IsInitializationComplete()) {
     // |backing_pref_store_| initialization failed.
     return mojom::PersistentPrefStoreConnection::New(
         nullptr, nullptr, backing_pref_store_->GetReadError(),
         backing_pref_store_->ReadOnly());
   }
   mojom::PersistentPrefStorePtr pref_store_ptr;
   mojom::PrefStoreObserverPtr observer;
   mojom::PrefStoreObserverRequest observer_request =
       mojo::MakeRequest(&observer);
   auto connection = base::MakeUnique<Connection>(
-      this, mojo::MakeRequest(&pref_store_ptr), std::move(observer));
+      this, mojo::MakeRequest(&pref_store_ptr), std::move(observer),
+      std::move(observed_prefs));
   auto* connection_ptr = connection.get();
   connections_.insert(std::make_pair(connection_ptr, std::move(connection)));
   return mojom::PersistentPrefStoreConnection::New(
       mojom::PrefStoreConnection::New(std::move(observer_request),
                                       backing_pref_store_->GetValues(), true),
       std::move(pref_store_ptr), backing_pref_store_->GetReadError(),
       backing_pref_store_->ReadOnly());
 }
 
 void PersistentPrefStoreImpl::OnPrefValueChanged(const std::string& key) {
@@ skipping 34 matching lines @@
 
 void PersistentPrefStoreImpl::ClearMutableValues() {
   backing_pref_store_->ClearMutableValues();
 }
 
 void PersistentPrefStoreImpl::OnConnectionError(Connection* connection) {
   connections_.erase(connection);
 }
 
 }  // namespace prefs