[Sync] Add support for automatic enabling of syncing tab favicons.

We add the sync_tab_favicons field to the nigori node and add support
for automatically enabling the feature when we receive a new nigori node.
Once we do enable the feature, the browser will only start writing favicons
after the next restart.

BUG=92728
TEST=using python testserver to enable sync tab favicons, then restarting.


Review URL: http://codereview.chromium.org/10235013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@134184 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 51 insertions, 7 deletions

diff --git a/sync/internal_api/sync_manager.cc b/sync/internal_api/sync_manager.cc
index d7d8c8a..f33fefa 100644
--- a/sync/internal_api/sync_manager.cc
+++ b/sync/internal_api/sync_manager.cc
@@ -52,6 +52,7 @@
 #include "sync/syncable/model_type_payload_map.h"
 #include "sync/syncable/syncable.h"
 #include "sync/util/cryptographer.h"
+#include "sync/util/experiments.h"
 #include "sync/util/get_session_name.h"
 #include "sync/util/time.h"
 
@@ -2478,7 +2479,7 @@ syncable::ModelTypeSet SyncManager::GetEncryptedDataTypesForTest() const {
   return GetEncryptedTypes(&trans);
 }
 
-bool SyncManager::ReceivedExperimentalTypes(syncable::ModelTypeSet* to_add)
+bool SyncManager::ReceivedExperiment(browser_sync::Experiments* experiments)
     const {
   ReadTransaction trans(FROM_HERE, GetUserShare());
   ReadNode node(&trans);
@@ -2486,11 +2487,16 @@ bool SyncManager::ReceivedExperimentalTypes(syncable::ModelTypeSet* to_add)
     DVLOG(1) << "Couldn't find Nigori node.";
     return false;
   }
+  bool found_experiment = false;
   if (node.GetNigoriSpecifics().sync_tabs()) {
-    to_add->Put(syncable::SESSIONS);
-    return true;
+    experiments->sync_tabs = true;
+    found_experiment = true;
+  }
+  if (node.GetNigoriSpecifics().sync_tab_favicons()) {
+    experiments->sync_tab_favicons = true;
+    found_experiment = true;
   }
-  return false;
+  return found_experiment;
 }
 
 bool SyncManager::HasUnsyncedItems() const {
diff --git a/sync/internal_api/sync_manager.h b/sync/internal_api/sync_manager.h
index 8288164..cfc05a0 100644
--- a/sync/internal_api/sync_manager.h
+++ b/sync/internal_api/sync_manager.h
@@ -25,6 +25,7 @@
 
 namespace browser_sync {
 class Encryptor;
+struct Experiments;
 class ExtensionsActivityMonitor;
 class JsBackend;
 class JsEventHandler;
@@ -591,10 +592,10 @@ class SyncManager {
   // Note: opens a transaction.  May be called from any thread.
   syncable::ModelTypeSet GetEncryptedDataTypesForTest() const;
 
-  // Reads the nigori node to determine if any experimental types should be
-  // enabled.
+  // Reads the nigori node to determine if any experimental features should
+  // be enabled.
   // Note: opens a transaction.  May be called on any thread.
-  bool ReceivedExperimentalTypes(syncable::ModelTypeSet* to_add) const;
+  bool ReceivedExperiment(browser_sync::Experiments* experiments) const;
 
   // Uses a read-only transaction to determine if the directory being synced has
   // any remaining unsynced items.  May be called on any thread.
diff --git a/sync/protocol/nigori_specifics.proto b/sync/protocol/nigori_specifics.proto
index 50f5014..8a0effd 100644
--- a/sync/protocol/nigori_specifics.proto
+++ b/sync/protocol/nigori_specifics.proto
@@ -90,5 +90,8 @@ message NigoriSpecifics {
   // User device information. Contains information about each device that has a
   // sync-enabled Chrome browser connected to the user account.
   repeated DeviceInformation device_information = 28;
+  
+  // Enable syncing favicons as part of tab sync.
+  optional bool sync_tab_favicons = 29;
 }
 
diff --git a/sync/protocol/proto_value_conversions.cc b/sync/protocol/proto_value_conversions.cc
index 70b3ea1..cb4b1e33 100644
--- a/sync/protocol/proto_value_conversions.cc
+++ b/sync/protocol/proto_value_conversions.cc
@@ -310,6 +310,7 @@ DictionaryValue* NigoriSpecificsToValue(
   SET_BOOL(sync_tabs);
   SET_BOOL(encrypt_everything);
   SET_REP(device_information, DeviceInformationToValue);
+  SET_BOOL(sync_tab_favicons);
   return value;
 }
 
diff --git a/sync/sync.gyp b/sync/sync.gyp
index 81c05f9..bc6c263 100644
--- a/sync/sync.gyp
+++ b/sync/sync.gyp
@@ -157,6 +157,7 @@
         'util/data_type_histogram.h',
         'util/encryptor.h',
         'util/enum_set.h',
+        'util/experiments.h',
         'util/extensions_activity_monitor.cc',
         'util/extensions_activity_monitor.h',
         'util/get_session_name.cc',
diff --git a/sync/util/experiments.h b/sync/util/experiments.h
new file mode 100644
index 0000000..7cd77af
--- /dev/null
+++ b/sync/util/experiments.h
@@ -0,0 +1,32 @@
+// Copyright (c) 2012 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.
+
+#ifndef SYNC_UTIL_EXPERIMENTS_
+#define SYNC_UTIL_EXPERIMENTS_
+#pragma once
+
+#include "sync/syncable/model_type.h"
+
+namespace browser_sync {
+
+// A structure to hold the enable status of experimental sync features.
+struct Experiments {
+  Experiments() : sync_tabs(false), sync_tab_favicons(false) {}
+
+  bool Matches(const Experiments& rhs) {
+    return (sync_tabs == rhs.sync_tabs) &&
+           (sync_tab_favicons == rhs.sync_tab_favicons);
+  }
+
+  // Enable the tab sync (SESSIONS) datatype.
+  bool sync_tabs;
+
+  // Enable syncing of favicons within tab sync (only has an effect if tab sync
+  // is already enabled). This takes effect on the next restart.
+  bool sync_tab_favicons;
+};
+
+}
+
+#endif  // SYNC_UTIL_EXPERIMENTS_