[TaskManager] Allow a Task to mutate its PID after creation

chrome/browser/task_manager/providers/task.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/providers/task.h"
 
 #include <stddef.h>
 
 #include "base/process/process.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_attributes_entry.h"
 #include "chrome/browser/profiles/profile_attributes_storage.h"
 #include "chrome/browser/profiles/profile_manager.h"
+#include "chrome/browser/task_manager/providers/task_provider_observer.h"
 #include "chrome/browser/task_manager/task_manager_observer.h"
 #include "content/public/common/result_codes.h"
 
 namespace task_manager {
 
 namespace {
 
 // The last ID given to the previously created task.
 int64_t g_last_id = 0;
 
+base::ProcessId DetermineProcessId(base::ProcessHandle handle,
+                                   base::ProcessId process_id) {
+  if (process_id != base::kNullProcessId)
+    return process_id;
+  return base::GetProcId(handle);
+}
+
 }  // namespace
 
 Task::Task(const base::string16& title,
            const std::string& rappor_sample,
            const gfx::ImageSkia* icon,
            base::ProcessHandle handle,
            base::ProcessId process_id)
     : task_id_(g_last_id++),
       network_usage_(-1),
       current_byte_count_(-1),
       title_(title),
       rappor_sample_name_(rappor_sample),
       icon_(icon ? *icon : gfx::ImageSkia()),
       process_handle_(handle),
-      process_id_(process_id != base::kNullProcessId
-                      ? process_id
-                      : base::GetProcId(handle)) {}
+      process_id_(DetermineProcessId(handle, process_id)) {}
 
 Task::~Task() {}
 
 // static
 base::string16 Task::GetProfileNameFromProfile(Profile* profile) {
   DCHECK(profile);
   ProfileAttributesEntry* entry;
   if (g_browser_process->profile_manager()->GetProfileAttributesStorage().
       GetProfileAttributesWithPath(profile->GetOriginalProfile()->GetPath(),
                                    &entry)) {
@@ skipping 24 matching lines @@
   if (current_byte_count_ == -1)
     return;
 
   network_usage_ =
       (current_byte_count_ * base::TimeDelta::FromSeconds(1)) / update_interval;
 
   // Reset the current byte count for this task.
   current_byte_count_ = 0;
 }
 
+void Task::UpdateProcessInfo(base::ProcessHandle handle,
+                             base::ProcessId process_id,
+                             TaskProviderObserver* observer) {
+  process_id = DetermineProcessId(handle, process_id);
+
+  // Don't remove the task if there is no change to the process ID.
+  if (process_id == process_id_)
+    return;
+
+  // TaskManagerImpl and TaskGroup implementations assume that a process ID is
+  // consistent for the lifetime of a Task. So to change the process ID,
+  // temporarily unregister this Task.
+  observer->TaskRemoved(this);
+  process_handle_ = handle;
+  process_id_ = process_id;
+  observer->TaskAdded(this);
+}
+
 void Task::OnNetworkBytesRead(int64_t bytes_read) {
   if (current_byte_count_ == -1)
     current_byte_count_ = 0;
 
   current_byte_count_ += bytes_read;
 }
 
 void Task::GetTerminationStatus(base::TerminationStatus* out_status,
                                 int* out_error_code) const {
   DCHECK(out_status);
@@ skipping 49 matching lines @@
 
 int Task::GetKeepaliveCount() const {
   return -1;
 }
 
 bool Task::ReportsNetworkUsage() const {
   return network_usage_ != -1;
 }
 
 }  // namespace task_manager