Pref service: have Mash and Chrome connect to the right pref stores

services/preferences/pref_store_manager_impl.cc

Index: services/preferences/pref_store_manager_impl.cc
diff --git a/services/preferences/pref_store_manager_impl.cc b/services/preferences/pref_store_manager_impl.cc
index 8c428ee7f474c527fdc8e20e4e71be2a801ab38a..ca0ea378f1f3845afeb9f13a15800bb216c42877 100644
--- a/services/preferences/pref_store_manager_impl.cc
+++ b/services/preferences/pref_store_manager_impl.cc
@@ -4,6 +4,7 @@
 
 #include "services/preferences/pref_store_manager_impl.h"
 
+#include <algorithm>
 #include <utility>
 
 #include "base/memory/ref_counted.h"
@@ -20,8 +21,8 @@ namespace prefs {
 namespace {
 
 using ConnectCallback = mojom::PrefStoreConnector::ConnectCallback;
-using PrefStorePtrs =
-    std::unordered_map<PrefValueStore::PrefStoreType, mojom::PrefStorePtr>;
+using PrefStorePtrs = std::unordered_map<PrefValueStore::PrefStoreType,
+                                         const mojom::PrefStorePtr&>;
 
 // Used to make sure all pref stores have been registered before replying to any
 // Connect calls.
@@ -119,6 +120,19 @@ PrefStoreManagerImpl::PrefStoreManagerImpl(
 
 PrefStoreManagerImpl::~PrefStoreManagerImpl() = default;
 
+PrefStoreManagerImpl::PendingConnect::PendingConnect(
+    mojom::PrefRegistryPtr pref_registry_in,
+    std::vector<PrefValueStore::PrefStoreType> already_connected_types_in,
+    const ConnectCallback& callback_in)
+    : pref_registry(std::move(pref_registry_in)),
+      already_connected_types(std::move(already_connected_types_in)),
+      callback(callback_in) {}
+
+PrefStoreManagerImpl::PendingConnect::PendingConnect(PendingConnect&& other) =
+    default;
+
+PrefStoreManagerImpl::PendingConnect::~PendingConnect() = default;
+
 void PrefStoreManagerImpl::Register(PrefValueStore::PrefStoreType type,
                                     mojom::PrefStorePtr pref_store_ptr) {
   if (expected_pref_stores_.count(type) == 0) {
@@ -139,13 +153,15 @@ void PrefStoreManagerImpl::Register(PrefValueStore::PrefStoreType type,
   }
 }
 
-void PrefStoreManagerImpl::Connect(mojom::PrefRegistryPtr pref_registry,
-                                   const ConnectCallback& callback) {
+void PrefStoreManagerImpl::Connect(
+    mojom::PrefRegistryPtr pref_registry,
+    const std::vector<PrefValueStore::PrefStoreType>& already_connected_types,
+    const ConnectCallback& callback) {
   if (AllConnected()) {
-    ConnectImpl(std::move(pref_registry), callback);
+    ConnectImpl(std::move(pref_registry), already_connected_types, callback);
   } else {
-    pending_connects_.push_back(
-        std::make_pair(callback, std::move(pref_registry)));
+    pending_connects_.emplace_back(std::move(pref_registry),
+                                   already_connected_types, callback);
   }
 }
 
@@ -211,12 +227,15 @@ bool PrefStoreManagerImpl::AllConnected() const {
 
 void PrefStoreManagerImpl::ProcessPendingConnects() {
   for (auto& connect : pending_connects_)
-    ConnectImpl(std::move(connect.second), connect.first);
+    ConnectImpl(std::move(connect.pref_registry),
+                connect.already_connected_types, connect.callback);
   pending_connects_.clear();
 }
 
-void PrefStoreManagerImpl::ConnectImpl(mojom::PrefRegistryPtr pref_registry,
-                                       const ConnectCallback& callback) {
+void PrefStoreManagerImpl::ConnectImpl(
+    mojom::PrefRegistryPtr pref_registry,
+    const std::vector<PrefValueStore::PrefStoreType>& already_connected_types,
+    const ConnectCallback& callback) {
   std::vector<std::string> observed_prefs;
   for (auto& registration : pref_registry->registrations) {
     observed_prefs.push_back(registration.first);
@@ -230,8 +249,18 @@ void PrefStoreManagerImpl::ConnectImpl(mojom::PrefRegistryPtr pref_registry,
     else
       defaults_->SetDefaultValue(key, std::move(default_value));
   }
+
+  // Only connect to pref stores the client isn't already connected to.
+  PrefStorePtrs ptrs;
+  for (const auto& entry : pref_store_ptrs_) {
+    if (std::find(already_connected_types.begin(),
+                  already_connected_types.end(),
+                  entry.first) == already_connected_types.end()) {
+      ptrs.insert(entry);
+    }
+  }
   ConnectionBarrier::Create(
-      pref_store_ptrs_,
+      ptrs,
       persistent_pref_store_->CreateConnection(
           PersistentPrefStoreImpl::ObservedPrefs(observed_prefs.begin(),
                                                  observed_prefs.end())),