Make SDCH dictionaries persistent across browser restart.

chrome/browser/profiles/profile_impl_io_data.cc

Index: chrome/browser/profiles/profile_impl_io_data.cc
diff --git a/chrome/browser/profiles/profile_impl_io_data.cc b/chrome/browser/profiles/profile_impl_io_data.cc
index e2cb0ec4ef3e10a0c01acdce32227b3e2d5591a7..835f8f88fdfb9a7a235b327f587e03fe4910e71a 100644
--- a/chrome/browser/profiles/profile_impl_io_data.cc
+++ b/chrome/browser/profiles/profile_impl_io_data.cc
@@ -4,11 +4,15 @@
 
 #include "chrome/browser/profiles/profile_impl_io_data.h"
 
+#include <set>
+
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
+#include "base/prefs/json_pref_store.h"
+#include "base/prefs/pref_filter.h"
 #include "base/prefs/pref_member.h"
 #include "base/prefs/pref_service.h"
 #include "base/profiler/scoped_tracker.h"
@@ -90,6 +94,20 @@ net::BackendType ChooseCacheBackendType() {
 #endif
 }
 
+bool ShouldUseSdchPersistence() {
+  const std::string group =
+      base::FieldTrialList::FindFullName("SdchPersistence");
+  const base::CommandLine* command_line =
+      base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kEnableSdchPersistence)) {
+    return true;
+  }
+  if (command_line->HasSwitch(switches::kDisableSdchPersistence)) {
+    return false;
+  }
+  return group == "Enabled";
+}
+
 }  // namespace
 
 using content::BrowserThread;
@@ -424,6 +442,16 @@ void ProfileImplIOData::InitializeInternal(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "436671 ProfileImplIOData::InitializeInternal"));
 
+  // Set up a persistent store for use by the network stack on the IO thread.
+  base::FilePath network_json_store_filepath(
+      profile_path_.Append(chrome::kNetworkPersistentStateFilename));
+  network_json_store_ = new JsonPrefStore(
+      network_json_store_filepath,
+      JsonPrefStore::GetTaskRunnerForFile(network_json_store_filepath,
+                                          BrowserThread::GetBlockingPool()),
+      scoped_ptr<PrefFilter>());
+  network_json_store_->ReadPrefsAsync(nullptr);

[Randy Smith (Not in Mondays), 2015/02/23 21:23:49]

Given that there's concern around the costs of this during startup, as well as
actually loading in the dictionaries, would it be worthwhile expanding the Finch
trial to have a group that doesn't do the async prefs read as well?

[Elly Fong-Jones, 2015/03/03 21:37:44]

Talked about this offline and decided not to do it.

+
   net::URLRequestContext* main_context = main_request_context();
 
   IOThread* const io_thread = profile_params->io_thread;
@@ -612,6 +640,9 @@ void ProfileImplIOData::InitializeInternal(
   sdch_manager_.reset(new net::SdchManager);
   sdch_policy_.reset(new net::SdchOwner(sdch_manager_.get(), main_context));
   main_context->set_sdch_manager(sdch_manager_.get());
+  if (ShouldUseSdchPersistence()) {
+    sdch_policy_->EnablePersistentStorage(network_json_store_.get());
+  }
 
   // Create a media request context based on the main context, but using a
   // media cache.  It shares the same job factory as the main context.