Query NaCl processes' GDB debug port on the correct thread.

chrome/browser/task_manager/sampling/task_group.cc

Index: chrome/browser/task_manager/sampling/task_group.cc
diff --git a/chrome/browser/task_manager/sampling/task_group.cc b/chrome/browser/task_manager/sampling/task_group.cc
index a7a0d11116ec0b15b4f361873cfdc146174b294e..dfb15a536ee74b5b06001286e86c389e0eb68b87 100644
--- a/chrome/browser/task_manager/sampling/task_group.cc
+++ b/chrome/browser/task_manager/sampling/task_group.cc
@@ -31,7 +31,7 @@ const int kBackgroundRefreshTypesMask =
 #if defined(OS_LINUX)
     REFRESH_TYPE_FD_COUNT |
 #endif  // defined(OS_LINUX)
-    REFRESH_TYPE_PRIORITY;
+    REFRESH_TYPE_NACL | REFRESH_TYPE_PRIORITY;

[Wez, 2017/01/23 21:49:10]

IIUC getting these wrong should mean that we never signal completion of the
refresh back to the TaskManagerImpl, if one or more non-background refresh flags
are set - I think we can add a TaskManagerImpl test-case for that, but adding
one directly on TaskGroup might be cleaner?

[afakhry, 2017/02/09 01:26:59]

Your understanding is correct. 

That's why you must keep the REFRESH_TYPE_NACL here inside an #if
!defined(DISABLE_NACL) for the:

expected_on_bg_done_flags_ = refresh_flags & kBackgroundRefreshTypesMask;

that we do at the beginning of Refresh() to work properly if the user requested
REFRESH_TYPE_NACL while nacl is disabled.

Thanks for suggesting the test case. I think it would be easier to test
TaskGroup directly.

 
 #if defined(OS_WIN)
 // Gets the GDI and USER Handles on Windows at one shot.
@@ -89,7 +89,7 @@ TaskGroup::TaskGroup(
       user_peak_handles_(-1),
 #endif  // defined(OS_WIN)
 #if !defined(DISABLE_NACL)
-      nacl_debug_stub_port_(-1),
+      nacl_debug_stub_port_(nacl::kGdbDebugStubPortUnknown),
 #endif  // !defined(DISABLE_NACL)
       idle_wakeups_per_second_(-1),
 #if defined(OS_LINUX)
@@ -176,7 +176,8 @@ void TaskGroup::Refresh(const gpu::VideoMemoryUsageStats& gpu_memory_stats,
   }
 #endif  // defined(OS_WIN)
 
-  // 4- Refresh the NACL debug stub port (if enabled).
+// 4- Refresh the NACL debug stub port (if enabled). This calls out to
+//    NaClBrowser on the browser's IO thread, completing asynchronously.
 #if !defined(DISABLE_NACL)
   if (TaskManagerObserver::IsResourceRefreshEnabled(REFRESH_TYPE_NACL,
                                                     refresh_flags) &&
@@ -255,14 +256,28 @@ void TaskGroup::RefreshWindowsHandles() {
 #endif  // defined(OS_WIN)
 }
 
-void TaskGroup::RefreshNaClDebugStubPort(int child_process_unique_id) {
 #if !defined(DISABLE_NACL)
-  nacl::NaClBrowser* nacl_browser = nacl::NaClBrowser::GetInstance();
-  nacl_debug_stub_port_ =
-      nacl_browser->GetProcessGdbDebugStubPort(child_process_unique_id);
-#endif  // !defined(DISABLE_NACL)
+static int GetNaClDebugStubPortOnIoThread(int process_id) {
+  return nacl::NaClBrowser::GetInstance()->GetProcessGdbDebugStubPort(
+      process_id);
+}

[afakhry, 2017/02/09 01:26:59]

Nit: To keep the organization of the current code consistent, can you please
move
this to the anonymous namespace?

Thanks for naming it ...OnIoThread(), this is clear now. I still think adding a
DCHECK to assert running on IO thread is more future proof.

+
+void TaskGroup::RefreshNaClDebugStubPort(int child_process_unique_id) {
+  content::BrowserThread::PostTaskAndReplyWithResult(
+      content::BrowserThread::IO, FROM_HERE,
+      base::Bind(&GetNaClDebugStubPortOnIoThread, child_process_unique_id),
+      base::Bind(&TaskGroup::OnRefreshNaClDebugStubPortDone,
+                 weak_ptr_factory_.GetWeakPtr()));
 }
 
+void TaskGroup::OnRefreshNaClDebugStubPortDone(int nacl_debug_stub_port) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
+  nacl_debug_stub_port_ = nacl_debug_stub_port;
+  OnBackgroundRefreshTypeFinished(REFRESH_TYPE_NACL);
+}
+#endif  // !defined(DISABLE_NACL)
+
 void TaskGroup::OnCpuRefreshDone(double cpu_usage) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);