Control TaskScheduler initialization params in renderers via field trial.

components/task_scheduler_util/common/variations_util.h

Index: components/task_scheduler_util/common/variations_util.h
diff --git a/components/task_scheduler_util/common/variations_util.h b/components/task_scheduler_util/common/variations_util.h
index aa37d25b2391d370443412bc5607a3a014e2a4e5..9859a16cd659a4fd37040c54570994b8cfb1103d 100644
--- a/components/task_scheduler_util/common/variations_util.h
+++ b/components/task_scheduler_util/common/variations_util.h
@@ -9,9 +9,15 @@
 #include <string>
 #include <vector>
 
+#include "build/build_config.h"
+#include "base/strings/string_piece.h"
 #include "base/task_scheduler/scheduler_worker_pool_params.h"
 #include "base/threading/platform_thread.h"
 
+namespace base {
+class CommandLine;
+}
+
 namespace task_scheduler_util {
 
 class SchedulerImmutableWorkerPoolParams {
@@ -36,6 +42,19 @@ std::vector<base::SchedulerWorkerPoolParams> GetWorkerPoolParams(
         constant_worker_pool_params_vector,
     const std::map<std::string, std::string>& variation_params);
 
+#if !defined(OS_IOS)
+// Serializes variation params from the BrowserScheduler field trial whose key
+// start with |prefix| to the --task-scheduler-variation-params switch of
+// |command_line|.
+void AddVariationParamsToCommandLine(base::StringPiece key_prefix,
+                                     base::CommandLine* command_line);
+
+// Returns a map of key-value pairs deserialized from the
+// --task-scheduler-variation-params switch of |command_line|.
+std::map<std::string, std::string> GetVariationParamsFromCommandLine(
+    const base::CommandLine& command_line);
+#endif  // !defined(OS_IOS)
+
 }  // namespace task_scheduler_util
 
 #endif  // COMPONENTS_TASK_SCHEDULER_UTIL_COMMON_VARIATIONS_UTIL_H_