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

chrome/browser/task_manager/sampling/task_group.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/task_manager/sampling/task_group.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/bind.h"
@@ skipping 72 matching lines @@
       gpu_memory_(-1),
       memory_state_(base::MemoryState::UNKNOWN),
       per_process_network_usage_(-1),
 #if defined(OS_WIN)
       gdi_current_handles_(-1),
       gdi_peak_handles_(-1),
       user_current_handles_(-1),
       user_peak_handles_(-1),
 #endif  // defined(OS_WIN)
 #if !defined(DISABLE_NACL)
-      nacl_debug_stub_port_(-1),
+      nacl_debug_stub_port_(nacl::kGdbDebugStubPortUnknown),

[afakhry, 2017/01/23 17:41:55]

While we are here, can you please revise the expectation of the shown text here:
https://cs.chromium.org/chromium/src/chrome/browser/ui/task_manager/task_mana...

Are we showing the correct text? nacl::kGdbDebugStubPortUnknown shows the text
"Unknown". nacl::kGdbDebugStubPortUnused shows the text N/A text "-". -2, which
we use when NaCl debugging is disabled, shows the text "Disabled".

Your change here doesn't change the behavior at all since
nacl::kGdbDebugStubPortUnknown == -1, but just to verify we're showing the right
meaningful thing.

[Wez, 2017/01/23 19:21:01]

Hmmm, GetNaClPortText() doesn't need the -2 case, since it'll only be called if
NaCl debug ports are enabled; I'll update the impl to remove -2. Unfortunately
the enabled flag is not available to DCHECK there.

That said, perhaps it would be cleaner to have the TaskGroup sampler code "know"
that NaCl debug ports are disabled, and return kDisabled, kUnknown, kUnused, or
a value, to simplify the table model implementation?

 #endif  // !defined(DISABLE_NACL)
       idle_wakeups_per_second_(-1),
 #if defined(OS_LINUX)
       open_fd_count_(-1),
 #endif  // defined(OS_LINUX)
       gpu_memory_has_duplicates_(false),
       is_backgrounded_(false),
       weak_ptr_factory_(this) {
   scoped_refptr<TaskGroupSampler> sampler(
       new TaskGroupSampler(base::Process::Open(proc_id),
@@ skipping 147 matching lines @@
 #if defined(OS_WIN)
   GetWindowsHandles(process_handle_,
                     &gdi_current_handles_,
                     &gdi_peak_handles_,
                     &user_current_handles_,
                     &user_peak_handles_);
 #endif  // defined(OS_WIN)
 }
 
 #if !defined(DISABLE_NACL)
+static int GetNaClDebugStubPort(int process_id) {

[afakhry, 2017/01/23 17:41:55]

Can you please add a DCHECK_CURRENTLY_ON(content::BrowserThread::IO); to make it
clear?

[Wez, 2017/01/23 19:21:02]

I'd prefer to express that via the name, since this is a static function sitting
alongside its only caller, so a DCHECK seems overkill.

+  return nacl::NaClBrowser::GetInstance()->GetProcessGdbDebugStubPort(
+      process_id);
+}
+
 void TaskGroup::RefreshNaClDebugStubPort(int child_process_unique_id) {
-  nacl::NaClBrowser* nacl_browser = nacl::NaClBrowser::GetInstance();
   content::BrowserThread::PostTaskAndReplyWithResult(
       content::BrowserThread::IO, FROM_HERE,
-      base::Bind(&nacl::NaClBrowser::GetProcessGdbDebugStubPort,
-                 base::Unretained(nacl_browser), child_process_unique_id),
+      base::Bind(&GetNaClDebugStubPort, 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);
 }
@@ skipping 67 matching lines @@
 
 void TaskGroup::OnBackgroundRefreshTypeFinished(int64_t finished_refresh_type) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   current_on_bg_done_flags_ |= finished_refresh_type;
   if (AreBackgroundCalculationsDone())
     on_background_calculations_done_.Run();
 }
 
 }  // namespace task_manager