Revert 196116 "Sync: Turn on full history sync by default."

> Sync: Turn on full history sync by default.
> 
> Full history sync (and history delete directives) were off by default,
> but turned on in M27 via an experiment. This meant that history from
> signed-in devices was not visible on chrome://history until the browser
> was restarted.
> 
> This CL make full history sync enabled by default, but retains a
> command-line switch and about:flags option to disable it. It also
> removes the option to disable delete directives only, since that
> had the same effect as disabling full history sync.
> 
> TBR=brettw@chromium.org
> BUG=233098
> TEST=Start up Chrome in a fresh profile, and sign in. Go to
> chrome://history and ensure that it says "Showing history from your
> signed-in devices" at the top of the history page.
> 
> Review URL: https://chromiumcodereview.appspot.com/14344002

TBR=dubroy@chromium.org

Review URL: https://codereview.chromium.org/14387005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@196124 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 17 insertions, 0 deletions

diff --git a/sync/internal_api/public/util/experiments.h b/sync/internal_api/public/util/experiments.h
index c4b7dd5..a3b874b 100644
--- a/sync/internal_api/public/util/experiments.h
+++ b/sync/internal_api/public/util/experiments.h
@@ -12,6 +12,8 @@ namespace syncer {
 const char kKeystoreEncryptionTag[] = "keystore_encryption";
 const char kKeystoreEncryptionFlag[] = "sync-keystore-encryption";
 const char kAutofillCullingTag[] = "autofill_culling";
+const char kFullHistorySyncTag[] = "history_delete_directives";
+const char kFullHistorySyncFlag[] = "full-history-sync";
 const char kFaviconSyncTag[] = "favicon_sync";
 const char kFaviconSyncFlag[] = "enable-sync-favicons";
 
@@ -19,12 +21,14 @@ const char kFaviconSyncFlag[] = "enable-sync-favicons";
 struct Experiments {
   Experiments() : keystore_encryption(false),
                   autofill_culling(false),
+                  full_history_sync(false),
                   favicon_sync(false),
                   favicon_sync_limit(200) {}
 
   bool Matches(const Experiments& rhs) {
     return (keystore_encryption == rhs.keystore_encryption &&
             autofill_culling == rhs.autofill_culling &&
+            full_history_sync == rhs.full_history_sync &&
             favicon_sync == rhs.favicon_sync &&
             favicon_sync_limit == rhs.favicon_sync_limit);
   }
@@ -35,6 +39,9 @@ struct Experiments {
   // Enable deletion of expired autofill entries (if autofill sync is enabled).
   bool autofill_culling;
 
+  // Enable full history sync (and history delete directives) for this client.
+  bool full_history_sync;
+
   // Enable the favicons sync datatypes (favicon images and favicon tracking).
   bool favicon_sync;
 
diff --git a/sync/internal_api/sync_manager_impl.cc b/sync/internal_api/sync_manager_impl.cc
index fcccff6..0f807bc 100644
--- a/sync/internal_api/sync_manager_impl.cc
+++ b/sync/internal_api/sync_manager_impl.cc
@@ -1366,6 +1366,16 @@ bool SyncManagerImpl::ReceivedExperiment(Experiments* experiments) {
     found_experiment = true;
   }
 
+  ReadNode full_history_sync_node(&trans);
+  if (full_history_sync_node.InitByClientTagLookup(
+          syncer::EXPERIMENTS,
+          syncer::kFullHistorySyncTag) == BaseNode::INIT_OK &&
+      full_history_sync_node.GetExperimentsSpecifics().
+          history_delete_directives().enabled()) {
+    experiments->full_history_sync = true;
+    found_experiment = true;
+  }
+
   ReadNode favicon_sync_node(&trans);
   if (favicon_sync_node.InitByClientTagLookup(
           syncer::EXPERIMENTS,