Remove one thread hop while fetching matching rules

chrome/browser/android/data_usage/external_data_use_observer_bridge.cc

Index: chrome/browser/android/data_usage/external_data_use_observer_bridge.cc
diff --git a/chrome/browser/android/data_usage/external_data_use_observer_bridge.cc b/chrome/browser/android/data_usage/external_data_use_observer_bridge.cc
index 63e49661b8afda4599d288df6109992e2e8f4885..dbf3c5eae32fedbf32a1dff9b3bdf87b5aa2f10b 100644
--- a/chrome/browser/android/data_usage/external_data_use_observer_bridge.cc
+++ b/chrome/browser/android/data_usage/external_data_use_observer_bridge.cc
@@ -128,6 +128,10 @@ void ExternalDataUseObserverBridge::FetchMatchingRulesDone(
 
   data_use_tab_model_->RegisterURLRegexes(
       app_package_name_native, domain_path_regex_native, label_native);
+
+  io_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&ExternalDataUseObserver::OnFetchMatchingRulesDone,

[tbansal1, 2016/03/10 01:00:58]

Why is this callback needed?  This is not preventing 2 parallel calls to the
Java class because not all FetchMatchingRules() come from EDUO.

[Raj, 2016/03/10 02:13:34]

This callback updates the last_matching_rules_fetch_time_ in EDUO, which is
relied on in test MatchingRuleFetchOnControlAppInstall to identify whether rule
fetch is invoked.
I have changed the test to look at UMA to determine rule fetch was invoked.

+                            external_data_use_observer_));
 }
 
 void ExternalDataUseObserverBridge::ReportDataUse(
@@ -175,6 +179,15 @@ void ExternalDataUseObserverBridge::OnControlAppInstallStateChange(
   data_use_tab_model_->OnControlAppInstallStateChange(is_control_app_installed);
 }
 
+void ExternalDataUseObserverBridge::ShouldRegisterAsDataUseObserver(
+    bool should_register) const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  io_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&ExternalDataUseObserver::ShouldRegisterAsDataUseObserver,
+                 external_data_use_observer_, should_register));
+}
+
 bool RegisterExternalDataUseObserver(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }