Fixup DCHECK failure for enterprise reporting private API

In chrome.enterprisePrivate APIs, we use base::ThreadPool::PostTask in
few places. Unlike PostTaskAndReply, the callback is not posted on the
original thread. It causes CalledOnValidSequence check failure as we
returns the extension APIs on a different thread.

Fix the issue by remembering the original task runner to make sure the
extension APIs are responded in the main thread.

Change-Id: If3b69d56a0d8afc4c89da8104ddb24cceb07173e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2429544
Commit-Queue: Owen Min <zmin@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810623}

chrome/browser/extensions/api/enterprise_reporting_private/enterprise_reporting_private_api.cc

@@ -69,11 +69,22 @@ EnterpriseReportingPrivateGetPersistentSecretFunction::Run() {
           base::BindOnce(
               &EnterpriseReportingPrivateGetPersistentSecretFunction::
                   OnDataRetrieved,
-              this)));
+              this, base::ThreadTaskRunnerHandle::Get())));
   return RespondLater();
 }
 
 void EnterpriseReportingPrivateGetPersistentSecretFunction::OnDataRetrieved(
+    scoped_refptr<base::SequencedTaskRunner> task_runner,
+    const std::string& data,
+    long int status) {
+  task_runner->PostTask(
+      FROM_HERE,
+      base::BindOnce(
+          &EnterpriseReportingPrivateGetPersistentSecretFunction::SendResponse,
+          this, data, status));
+}
+
+void EnterpriseReportingPrivateGetPersistentSecretFunction::SendResponse(
     const std::string& data,
     long int status) {
   if (status == 0) {  // Success.
@@ -109,11 +120,22 @@ EnterpriseReportingPrivateGetDeviceDataFunction::Run() {
           &RetrieveDeviceData, params->id,
           base::BindOnce(
               &EnterpriseReportingPrivateGetDeviceDataFunction::OnDataRetrieved,
-              this)));
+              this, base::ThreadTaskRunnerHandle::Get())));
   return RespondLater();
 }
 
 void EnterpriseReportingPrivateGetDeviceDataFunction::OnDataRetrieved(
+    scoped_refptr<base::SequencedTaskRunner> task_runner,
+    const std::string& data,
+    RetrieveDeviceDataStatus status) {
+  task_runner->PostTask(
+      FROM_HERE,
+      base::BindOnce(
+          &EnterpriseReportingPrivateGetDeviceDataFunction::SendResponse, this,
+          data, status));
+}
+
+void EnterpriseReportingPrivateGetDeviceDataFunction::SendResponse(
     const std::string& data,
     RetrieveDeviceDataStatus status) {
   switch (status) {
@@ -156,11 +178,21 @@ EnterpriseReportingPrivateSetDeviceDataFunction::Run() {
           &StoreDeviceData, params->id, std::move(params->data),
           base::BindOnce(
               &EnterpriseReportingPrivateSetDeviceDataFunction::OnDataStored,
-              this)));
+              this, base::ThreadTaskRunnerHandle::Get())));
   return RespondLater();
 }
 
 void EnterpriseReportingPrivateSetDeviceDataFunction::OnDataStored(
+    scoped_refptr<base::SequencedTaskRunner> task_runner,
+    bool status) {
+  task_runner->PostTask(
+      FROM_HERE,
+      base::BindOnce(
+          &EnterpriseReportingPrivateSetDeviceDataFunction::SendResponse, this,
+          status));
+}
+
+void EnterpriseReportingPrivateSetDeviceDataFunction::SendResponse(
     bool status) {
   if (status) {
     VLOG(1) << "The Endpoint Verification data was stored.";

chrome/browser/extensions/api/enterprise_reporting_private/enterprise_reporting_private_api.h

@@ -54,7 +54,11 @@ class EnterpriseReportingPrivateGetPersistentSecretFunction
   ExtensionFunction::ResponseAction Run() override;
 
   // Callback once the data was retrieved from the file.
-  void OnDataRetrieved(const std::string& data, long int status);
+  void OnDataRetrieved(scoped_refptr<base::SequencedTaskRunner> task_runner,
+                       const std::string& data,
+                       long int status);
+
+  void SendResponse(const std::string& data, long int status);
 };
 
 class EnterpriseReportingPrivateGetDeviceDataFunction
@@ -76,8 +80,11 @@ class EnterpriseReportingPrivateGetDeviceDataFunction
   ExtensionFunction::ResponseAction Run() override;
 
   // Callback once the data was retrieved from the file.
-  void OnDataRetrieved(const std::string& data,
+  void OnDataRetrieved(scoped_refptr<base::SequencedTaskRunner> task_runner,
+                       const std::string& data,
                        RetrieveDeviceDataStatus status);
+
+  void SendResponse(const std::string& data, RetrieveDeviceDataStatus status);
 };
 
 class EnterpriseReportingPrivateSetDeviceDataFunction
@@ -99,7 +106,10 @@ class EnterpriseReportingPrivateSetDeviceDataFunction
   ExtensionFunction::ResponseAction Run() override;
 
   // Callback once the data was stored to the file.
-  void OnDataStored(bool status);
+  void OnDataStored(scoped_refptr<base::SequencedTaskRunner> task_runner,
+                    bool status);
+
+  void SendResponse(bool status);
 };
 
 class EnterpriseReportingPrivateGetDeviceInfoFunction