[Sync] Allow sync start without sign-in if the local sync backend is on.

chrome/browser/sync/profile_sync_service_factory.cc

Index: chrome/browser/sync/profile_sync_service_factory.cc
diff --git a/chrome/browser/sync/profile_sync_service_factory.cc b/chrome/browser/sync/profile_sync_service_factory.cc
index e36d7d87afb59df62a884f5d4984f52ac4917199..ae98f69631b6d0d0ddce0a7cff05773aae9fea3b 100644
--- a/chrome/browser/sync/profile_sync_service_factory.cc
+++ b/chrome/browser/sync/profile_sync_service_factory.cc
@@ -8,6 +8,7 @@
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
+#include "base/path_service.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "chrome/browser/autofill/personal_data_manager_factory.h"
@@ -31,6 +32,7 @@
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "chrome/browser/web_data_service_factory.h"
 #include "chrome/common/channel_info.h"
+#include "components/browser_sync/browser_sync_switches.h"
 #include "components/browser_sync/profile_sync_components_factory_impl.h"
 #include "components/browser_sync/profile_sync_service.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
@@ -74,6 +76,11 @@ void UpdateNetworkTime(const base::Time& network_time,
                  latency, base::TimeTicks::Now()));
 }
 
+#if defined(OS_WIN)
+static const base::FilePath::CharType kLoopbackServerBackendFilename[] =
+    FILE_PATH_LITERAL("profile.pb");
+#endif
+
 }  // anonymous namespace
 
 // static
@@ -144,33 +151,79 @@ KeyedService* ProfileSyncServiceFactory::BuildServiceInstanceFor(
 
   Profile* profile = Profile::FromBrowserContext(context);
 
-  SigninManagerBase* signin = SigninManagerFactory::GetForProfile(profile);
-
-  // Always create the GCMProfileService instance such that we can listen to
-  // the profile notifications and purge the GCM store when the profile is
-  // being signed out.
-  gcm::GCMProfileServiceFactory::GetForProfile(profile);
-
-  // TODO(atwilson): Change AboutSigninInternalsFactory to load on startup
-  // once http://crbug.com/171406 has been fixed.
-  AboutSigninInternalsFactory::GetForProfile(profile);
-
-  init_params.signin_wrapper =
-      base::MakeUnique<SupervisedUserSigninManagerWrapper>(profile, signin);
-  init_params.oauth2_token_service =
-      ProfileOAuth2TokenServiceFactory::GetForProfile(profile);
-  init_params.gaia_cookie_manager_service =
-      GaiaCookieManagerServiceFactory::GetForProfile(profile);
-
-  // TODO(tim): Currently, AUTO/MANUAL settings refer to the *first* time sync
-  // is set up and *not* a browser restart for a manual-start platform (where
-  // sync has already been set up, and should be able to start without user
-  // intervention). We can get rid of the browser_default eventually, but
-  // need to take care that ProfileSyncService doesn't get tripped up between
-  // those two cases. Bug 88109.
-  init_params.start_behavior = browser_defaults::kSyncAutoStarts
-                                   ? ProfileSyncService::AUTO_START
-                                   : ProfileSyncService::MANUAL_START;
+  init_params.network_time_update_callback = base::Bind(&UpdateNetworkTime);
+  init_params.base_directory = profile->GetPath();
+  init_params.url_request_context = profile->GetRequestContext();
+  init_params.debug_identifier = profile->GetDebugName();
+  init_params.channel = chrome::GetChannel();
+  init_params.blocking_pool = content::BrowserThread::GetBlockingPool();
+  init_params.local_sync_backend_enabled = false;
+
+#if defined(OS_WIN)
+  init_params.local_sync_backend_enabled =
+      base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableLocalSyncBackend);
+
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(

[Nicolas Zea, 2016/11/19 00:36:42]

should all of this logic be dependent on local_sync_backend_enabled? Perhaps put
within a conditional?

[pastarmovj, 2016/11/22 12:38:08]

Done.

+          switches::kLocalSyncBackendDir)) {
+    init_params.local_sync_backend_folder =
+        base::CommandLine::ForCurrentProcess()->GetSwitchValuePath(
+            switches::kLocalSyncBackendDir);
+  } else {
+    // TODO(pastarmovj): Add DIR_ROAMING_USER_DATA to PathService to simplify
+    // this code and move the logic in its right place. See crbug/657810.
+    CHECK(base::PathService::Get(base::DIR_APP_DATA,
+                                 &init_params.local_sync_backend_folder));
+    init_params.local_sync_backend_folder =
+        init_params.local_sync_backend_folder.Append(
+            FILE_PATH_LITERAL("Chrome/User Data"));
+  }
+  // This code as it is now will assume the same profile order is present on all
+  // machines, which is not a given. It is to be defined if only the Default
+  // profile should get this treatment or all profile as is the case now. The
+  // solution for now will be to assume profiles are created in the same order
+  // on all machines and in the future decide if only the Default one should be
+  // considered roamed.
+  init_params.local_sync_backend_folder =
+      init_params.local_sync_backend_folder.Append(
+          init_params.base_directory.BaseName());
+  init_params.local_sync_backend_folder =
+      init_params.local_sync_backend_folder.Append(
+          kLoopbackServerBackendFilename);
+#endif  // defined(OS_WIN)
+
+  if (!init_params.local_sync_backend_enabled) {
+    SigninManagerBase* signin = SigninManagerFactory::GetForProfile(profile);
+
+    // Always create the GCMProfileService instance such that we can listen to
+    // the profile notifications and purge the GCM store when the profile is
+    // being signed out.
+    gcm::GCMProfileServiceFactory::GetForProfile(profile);
+
+    // TODO(atwilson): Change AboutSigninInternalsFactory to load on startup
+    // once http://crbug.com/171406 has been fixed.
+    AboutSigninInternalsFactory::GetForProfile(profile);
+
+    init_params.signin_wrapper =
+        base::MakeUnique<SupervisedUserSigninManagerWrapper>(profile, signin);
+    init_params.oauth2_token_service =
+        ProfileOAuth2TokenServiceFactory::GetForProfile(profile);
+    init_params.gaia_cookie_manager_service =
+        GaiaCookieManagerServiceFactory::GetForProfile(profile);
+
+    // TODO(tim): Currently, AUTO/MANUAL settings refer to the *first* time sync
+    // is set up and *not* a browser restart for a manual-start platform (where
+    // sync has already been set up, and should be able to start without user
+    // intervention). We can get rid of the browser_default eventually, but
+    // need to take care that ProfileSyncService doesn't get tripped up between
+    // those two cases. Bug 88109.
+    init_params.start_behavior = browser_defaults::kSyncAutoStarts
+                                     ? ProfileSyncService::AUTO_START
+                                     : ProfileSyncService::MANUAL_START;
+  } else {
+    // In local mode none of the sign-in stuff is required.
+    init_params.start_behavior = ProfileSyncService::AUTO_START;

[Nicolas Zea, 2016/11/19 00:36:42]

I think it's cleaner to move this up to the #if defined(OS_WIN) section

[pastarmovj, 2016/11/22 12:38:08]

Done.

Btw technically all of the above can always be initialized (up to setting the
right start_behavior). The whole reason I put this in a condition here is to
more easily catch errors where the network is used when in local mode. If you'd
rather wish that we don't do this here I can remove this condition altogether.

+  }
 
   if (!client_factory_) {
     init_params.sync_client =
@@ -179,13 +232,6 @@ KeyedService* ProfileSyncServiceFactory::BuildServiceInstanceFor(
     init_params.sync_client = client_factory_->Run(profile);
   }
 
-  init_params.network_time_update_callback = base::Bind(&UpdateNetworkTime);
-  init_params.base_directory = profile->GetPath();
-  init_params.url_request_context = profile->GetRequestContext();
-  init_params.debug_identifier = profile->GetDebugName();
-  init_params.channel = chrome::GetChannel();
-  init_params.blocking_pool = content::BrowserThread::GetBlockingPool();
-
   auto pss = base::MakeUnique<ProfileSyncService>(std::move(init_params));
 
   // Will also initialize the sync client.