cronet: Support setting feature list from experimental option

src/components/cronet/android/cronet_library_loader.cc

@@ -146,7 +146,8 @@ void PostTaskToInitThread(const base::Location& posted_from,
   g_init_task_executor->task_runner()->PostTask(posted_from, std::move(task));
 }
 
-void EnsureInitialized() {
+void EnsureInitialized(const char* /*enable_features*/,
+                       const char* /*disable_features*/) {
   if (g_init_task_executor) {
     // Ensure that init is done on the init thread.
     g_init_thread_init_done.Wait();

src/components/cronet/cronet_global_state.h

@@ -31,7 +31,8 @@ void PostTaskToInitThread(const base::Location& posted_from,
 // or binding to an existing thread, to run initialization and process
 // network notifications on. The implementation must be thread-safe and
 // idempotent, and must complete initialization before returning.
-void EnsureInitialized();
+void EnsureInitialized(const char* enable_features = nullptr,
+                       const char* disable_features = nullptr);
 
 // Creates a proxy config service appropriate for this platform that fetches the
 // system proxy settings. Cronet will call this API only after a prior call

src/components/cronet/cronet_global_state_stubs.cc

@@ -21,14 +21,18 @@ namespace cronet {
 
 namespace {
 
-scoped_refptr<base::SingleThreadTaskRunner> InitializeAndCreateTaskRunner() {
+scoped_refptr<base::SingleThreadTaskRunner> InitializeAndCreateTaskRunner(
+    const char* enable_features,
+    const char* disable_features) {
 // Cronet tests sets AtExitManager as part of TestSuite, so statically linked
 // library is not allowed to set its own.
 #if !defined(CRONET_TESTS_IMPLEMENTATION)
   std::ignore = new base::AtExitManager;
 #endif
 
-  base::FeatureList::InitializeInstance(std::string(), std::string());
+  base::FeatureList::InitializeInstance(
+      enable_features ? enable_features : "",
+      disable_features ? disable_features : "");
 
   // Note that in component builds this ThreadPoolInstance will be shared with
   // the calling process, if it also depends on //base. In particular this means
@@ -39,16 +43,19 @@ scoped_refptr<base::SingleThreadTaskRunner> InitializeAndCreateTaskRunner() {
   return base::ThreadPool::CreateSingleThreadTaskRunner({});
 }
 
-base::SingleThreadTaskRunner* InitTaskRunner() {
+base::SingleThreadTaskRunner* InitTaskRunner(
+    const char* enable_features = nullptr,
+    const char* disable_features = nullptr) {
   static scoped_refptr<base::SingleThreadTaskRunner> init_task_runner =
-      InitializeAndCreateTaskRunner();
+      InitializeAndCreateTaskRunner(enable_features, disable_features);
   return init_task_runner.get();
 }
 
 }  // namespace
 
-void EnsureInitialized() {
-  std::ignore = InitTaskRunner();
+void EnsureInitialized(const char* enable_features,
+                       const char* disable_features) {
+  std::ignore = InitTaskRunner(enable_features, disable_features);
 }
 
 bool OnInitThread() {

src/components/cronet/native/engine.cc

@@ -7,6 +7,7 @@
 #include <unordered_set>
 #include <utility>
 
+#include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/files/file_path.h"
@@ -102,6 +103,25 @@ Cronet_EngineImpl::~Cronet_EngineImpl() {
 
 Cronet_RESULT Cronet_EngineImpl::StartWithParams(
     Cronet_EngineParamsPtr params) {
+  absl::optional<base::Value::DictStorage> experimental_options =
+      URLRequestContextConfig::ParseExperimentalOptions(
+          params->experimental_options);
+  if (experimental_options) {
+    const auto& iter = experimental_options->find("feature_list");
+    if (iter != experimental_options->end()) {
+      const base::Value& feature_list = iter->second;
+      if (feature_list.is_dict()) {
+        const std::string* enable_features =
+            feature_list.GetDict().FindString(switches::kEnableFeatures);
+        const std::string* disable_features =
+            feature_list.GetDict().FindString(switches::kDisableFeatures);
+        cronet::EnsureInitialized(
+            enable_features ? enable_features->c_str() : nullptr,
+            disable_features ? disable_features->c_str() : nullptr);
+      }
+    }
+  }
+
   cronet::EnsureInitialized();
   base::AutoLock lock(lock_);
 

src/components/cronet/url_request_context_config.cc

@@ -761,6 +761,15 @@ void URLRequestContextConfig::SetContextBuilderExperimentalOptions(
         continue;
       }
       // Handled in CronetContext::NetworkTasks::BuildDefaultURLRequestContext.
+    } else if (iter.first == "feature_list") {
+      if (!iter.second.is_dict()) {
+        LOG(ERROR) << "\"" << iter.first << "\" config params \"" << iter.second
+                   << "\" is not a dictionary value";
+        effective_experimental_options.erase(iter.first);
+        continue;
+      }
+      // Already handled in Cronet_EngineImpl::StartWithParams.
+      // Only checks and reports errors here.
     } else {
       LOG(WARNING) << "Unrecognized Cronet experimental option \"" << iter.first
                    << "\" with params \"" << iter.second;

src/components/cronet/url_request_context_config.h

@@ -216,6 +216,12 @@ struct URLRequestContextConfig {
       // not specify for other targets.
       absl::optional<double> network_thread_priority);
 
+  // Parses experimental options from their JSON format to the format used
+  // internally.
+  // Returns an empty optional if the operation was unsuccessful.
+  static absl::optional<base::Value::DictStorage> ParseExperimentalOptions(
+      std::string unparsed_experimental_options);
+
  private:
   URLRequestContextConfig(
       // Enable QUIC.
@@ -253,12 +259,6 @@ struct URLRequestContextConfig {
       // not specify for other targets.
       absl::optional<double> network_thread_priority);
 
-  // Parses experimental options from their JSON format to the format used
-  // internally.
-  // Returns an empty optional if the operation was unsuccessful.
-  static absl::optional<base::Value::DictStorage> ParseExperimentalOptions(
-      std::string unparsed_experimental_options);
-
   // Makes appropriate changes to settings in |this|.
   void SetContextConfigExperimentalOptions();