[Cronet] Enable persistence mode for Sdch

components/cronet/android/cronet_url_request_context_adapter.cc

 // Copyright 2014 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.
 
 #include "components/cronet/android/cronet_url_request_context_adapter.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/bind.h"
 #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"
 #include "jni/CronetUrlRequestContext_jni.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
 #include "net/base/network_delegate_impl.h"
 #include "net/http/http_auth_handler_factory.h"
 #include "net/log/write_to_file_net_log_observer.h"
 #include "net/proxy/proxy_service.h"
@@ skipping 73 matching lines @@
     return false;
   }
 
   bool OnCanThrottleRequest(const net::URLRequest& request) const override {
     return false;
   }
 
   DISALLOW_COPY_AND_ASSIGN(BasicNetworkDelegate);
 };
 
+void CreatePrefFileIfNeeded(base::FilePath filepath) {
+  if (base::PathExists(filepath))
+    return;
+  base::WriteFile(filepath, "{}", 2);

[mmenke, 2015/05/11 17:16:19]

Is this really needed?  I don't see any documentation on the subject.  Also, I
don't see any other consumers doing this.

[xunjieli, 2015/05/12 19:17:50]

Done. Thanks! I saw an error from json pref store complaining about no file
found, so I added this part. It turns out that error isn't critical, and a new
file is created anyway. I will remove this part.

+}
+
 }  // namespace
 
 namespace cronet {
 
 // Explicitly register static JNI functions.
 bool CronetUrlRequestContextAdapterRegisterJni(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 CronetURLRequestContextAdapter::CronetURLRequestContextAdapter(
@@ skipping 32 matching lines @@
         jcronet_url_request_context) {
   DCHECK(GetNetworkTaskRunner()->BelongsToCurrentThread());
   DCHECK(!is_context_initialized_);
   DCHECK(proxy_config_service_);
   // TODO(mmenke):  Add method to have the builder enable SPDY.
   net::URLRequestContextBuilder context_builder;
   context_builder.set_network_delegate(new BasicNetworkDelegate());
   context_builder.set_proxy_config_service(proxy_config_service_.release());
   config->ConfigureURLRequestContextBuilder(&context_builder);
 
+  // Only set up pref file if http disk cache is enabled.

[mef, 2015/05/12 16:39:17]

I think we should set pref file if storage_path is specified, regardless of http
cache settings.

[xunjieli, 2015/05/12 19:17:49]

Done.

+  if (!config->storage_path.empty() && !config->load_disable_cache) {
+    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(
+          base::Thread::Options(base::MessageLoop::TYPE_DEFAULT, 0));
+    }
+    file_thread_->task_runner()->PostTask(
+        FROM_HERE, base::Bind(&CreatePrefFileIfNeeded, filepath));
+    network_json_store_ = new JsonPrefStore(
+        filepath, file_thread_->task_runner(), scoped_ptr<PrefFilter>());
+    network_json_store_->ReadPrefsAsync(nullptr);

[mef, 2015/05/12 16:39:17]

It seems that prefstore should just fallback to empty prefs on non-existent
file:
https://code.google.com/p/chromium/codesearch#chromium/src/base/prefs/json_pr...

[xunjieli, 2015/05/12 19:17:50]

Done. Yes, you and Matt are both right about this part. Somehow I thought the
error was critical when I saw the print statement in the logs.

+    context_builder.SetFileTaskRunner(file_thread_->task_runner());
+  }
+
   context_.reset(context_builder.Build());
 
   default_load_flags_ = net::LOAD_DO_NOT_SAVE_COOKIES |
                         net::LOAD_DO_NOT_SEND_COOKIES;
   if (config->load_disable_cache)
     default_load_flags_ |= net::LOAD_DISABLE_CACHE;
 
   if (config->enable_sdch) {
     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.
   if (config->enable_quic) {
     context_->http_server_properties()
         ->SetAlternativeServiceProbabilityThreshold(0.0f);
     for (auto hint = config->quic_hints.begin();
          hint != config->quic_hints.end(); ++hint) {
       const URLRequestContextConfig::QuicHint& quic_hint = **hint;
       if (quic_hint.host.empty()) {
@@ skipping 157 matching lines @@
 }
 
 static jint SetMinLogLevel(JNIEnv* env, jclass jcaller, jint jlog_level) {
   jint old_log_level = static_cast<jint>(logging::GetMinLogLevel());
   // MinLogLevel is global, shared by all URLRequestContexts.
   logging::SetMinLogLevel(static_cast<int>(jlog_level));
   return old_log_level;
 }
 
 }  // namespace cronet