[Cronet] Enable persistence mode for Sdch

components/cronet/android/cronet_url_request_context_adapter.cc

Index: components/cronet/android/cronet_url_request_context_adapter.cc
diff --git a/components/cronet/android/cronet_url_request_context_adapter.cc b/components/cronet/android/cronet_url_request_context_adapter.cc
index ec52c9a4c1721a4219f836f1ef40024629276dd0..f1b00d147da8141646e0b4027eb0d075a53bd32b 100644
--- a/components/cronet/android/cronet_url_request_context_adapter.cc
+++ b/components/cronet/android/cronet_url_request_context_adapter.cc
@@ -10,6 +10,7 @@
 #include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
 #include "base/logging.h"
+#include "base/prefs/pref_filter.h"
 #include "base/single_thread_task_runner.h"
 #include "base/values.h"
 #include "components/cronet/url_request_context_config.h"
@@ -155,6 +156,21 @@ void CronetURLRequestContextAdapter::InitializeOnNetworkThread(
   context_builder.set_proxy_config_service(proxy_config_service_.release());
   config->ConfigureURLRequestContextBuilder(&context_builder);
 
+  // Set up pref file if storage path is specified.
+  if (!config->storage_path.empty()) {
+    base::FilePath filepath(config->storage_path);
+    filepath = filepath.Append(FILE_PATH_LITERAL("local_prefs.json"));
+    if (!file_thread_) {
+      file_thread_.reset(new base::Thread("Network File Thread"));
+      file_thread_->StartWithOptions(

[mef, 2015/05/13 15:15:22]

nit: Thread::Start() seems to do the same thing.

[xunjieli, 2015/05/13 16:57:44]

Done.

+          base::Thread::Options(base::MessageLoop::TYPE_DEFAULT, 0));
+    }
+    network_json_store_ = new JsonPrefStore(

[mef, 2015/05/13 15:15:22]

nit: should it be called |json_pref_store_|?

[xunjieli, 2015/05/13 16:57:44]

Done.

+        filepath, file_thread_->task_runner(), scoped_ptr<PrefFilter>());
+    network_json_store_->ReadPrefsAsync(nullptr);
+    context_builder.SetFileTaskRunner(file_thread_->task_runner());
+  }
+
   context_.reset(context_builder.Build());
 
   default_load_flags_ = net::LOAD_DO_NOT_SAVE_COOKIES |
@@ -166,6 +182,8 @@ void CronetURLRequestContextAdapter::InitializeOnNetworkThread(
     DCHECK(context_->sdch_manager());
     sdch_owner_.reset(
         new net::SdchOwner(context_->sdch_manager(), context_.get()));
+    if (network_json_store_)
+      sdch_owner_->EnablePersistentStorage(network_json_store_.get());
   }
 
   // Currently (circa M39) enabling QUIC requires setting probability threshold.