RELAND: base/power_monitor: Add method to query thermal state

This CL relands crrev.com/c/2248729 that got reverted due to breaking
Mac Builder (dbg) and others (power_monitor_device_source_unittest.cc
did not include logging.h and it couldn't find 'DVLOG'). The original
CL description only said "wip wip" o_O, which is sad.

Essentially this CL adds a GetCurrentThermalState() to PowerMonitor to
actively retrieve the current ThermalState. The ThermalState is sent to
PowerObservers, but newly created clients still need to query it at
least one time.

TBR=fdoray@chromium.org since the diff is just an include file.


Bug: 1071431
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2248729Reviewed-by: Henrik Boström <hbos@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781322}

Change-Id: Ia62ddfd8afc167473f3456e4982f51eaa52a833f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2261363Reviewed-by: Miguel Casas <mcasas@chromium.org>
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781678}

base/BUILD.gn

@@ -2744,6 +2744,7 @@ test("base_unittests") {
     "parameter_pack_unittest.cc",
     "path_service_unittest.cc",
     "pickle_unittest.cc",
+    "power_monitor/power_monitor_device_source_unittest.cc",
     "power_monitor/power_monitor_unittest.cc",
     "process/environment_internal_unittest.cc",
     "process/memory_unittest.cc",

base/power_monitor/power_monitor.cc

@@ -52,6 +52,11 @@ bool PowerMonitor::IsProcessSuspended() {
   return g_is_process_suspended.load(std::memory_order_relaxed);
 }
 
+PowerObserver::DeviceThermalState PowerMonitor::GetCurrentThermalState() {
+  DCHECK(IsInitialized());
+  return GetInstance()->source_->GetCurrentThermalState();
+}
+
 void PowerMonitor::NotifyPowerStateChange(bool battery_in_use) {
   DCHECK(IsInitialized());
   DVLOG(1) << "PowerStateChange: " << (battery_in_use ? "On" : "Off")

base/power_monitor/power_monitor.h

@@ -56,6 +56,10 @@ class BASE_EXPORT PowerMonitor {
   // what is the real power state.
   static bool IsProcessSuspended();
 
+  // Read the current DeviceThermalState if known. Can be called on any thread.
+  // May only be called if the PowerMonitor has been initialized.
+  static PowerObserver::DeviceThermalState GetCurrentThermalState();
+
   // Uninitializes the PowerMonitor. Should be called at the end of any unit
   // test that mocks out the PowerMonitor, to avoid affecting subsequent tests.
   // There must be no live PowerObservers when invoked. Safe to call even if the

base/power_monitor/power_monitor_device_source.h

@@ -47,6 +47,8 @@ class BASE_EXPORT PowerMonitorDeviceSource : public PowerMonitorSource {
 #endif
 
  private:
+  friend class PowerMonitorDeviceSourceTest;
+
 #if defined(OS_WIN)
   // Represents a message-only window for power message handling on Windows.
   // Only allow PowerMonitor to create it.
@@ -86,6 +88,9 @@ class BASE_EXPORT PowerMonitorDeviceSource : public PowerMonitorSource {
   bool IsOnBatteryPowerImpl() override;
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
+  // PowerMonitorSource:
+  PowerObserver::DeviceThermalState GetCurrentThermalState() override;
+
   // Reference to the system IOPMrootDomain port.
   io_connect_t power_manager_port_ = IO_OBJECT_NULL;
 

base/power_monitor/power_monitor_device_source_mac.mm

@@ -51,6 +51,14 @@ bool PowerMonitorDeviceSource::IsOnBatteryPowerImpl() {
   return true;
 }
 
+PowerObserver::DeviceThermalState
+PowerMonitorDeviceSource::GetCurrentThermalState() {
+  if (@available(macOS 10.10.3, *)) {
+    return thermal_state_observer_->GetCurrentThermalState();
+  };
+  return PowerObserver::DeviceThermalState::kUnknown;
+}
+
 namespace {
 
 void BatteryEventCallback(void*) {

base/power_monitor/power_monitor_device_source_unittest.cc

+// Copyright 2020 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 "base/power_monitor/power_monitor_device_source.h"
+
+#include "base/logging.h"
+#include "base/power_monitor/power_monitor.h"
+#include "base/power_monitor/power_monitor_source.h"
+#include "build/build_config.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using DeviceThermalState = base::PowerObserver::DeviceThermalState;
+
+namespace base {
+
+class PowerMonitorDeviceSourceTest : public testing::Test {
+ public:
+  PowerMonitorDeviceSourceTest() = default;
+  ~PowerMonitorDeviceSourceTest() override = default;
+
+  DeviceThermalState GetCurrentThermalState() {
+    return power_monitor_device_source_.GetCurrentThermalState();
+  }
+
+  PowerMonitorDeviceSource power_monitor_device_source_;
+};
+
+TEST_F(PowerMonitorDeviceSourceTest, GetCurrentThermalState) {
+  const DeviceThermalState current_state = GetCurrentThermalState();
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+  // We cannot make assumptions on |current_state|. Print it out to use the var.
+  DVLOG(1) << PowerMonitorSource::DeviceThermalStateToString(current_state);
+#else
+  EXPECT_EQ(current_state, DeviceThermalState::kUnknown);
+#endif
+}
+
+}  // namespace base

base/power_monitor/power_monitor_source.cc

@@ -17,6 +17,10 @@ bool PowerMonitorSource::IsOnBatteryPower() {
   return on_battery_power_;
 }
 
+PowerObserver::DeviceThermalState PowerMonitorSource::GetCurrentThermalState() {
+  return PowerObserver::DeviceThermalState::kUnknown;
+}
+
 // static
 void PowerMonitorSource::ProcessPowerEvent(PowerEvent event_id) {
   if (!PowerMonitor::IsInitialized())

base/power_monitor/power_monitor_source.h

@@ -31,6 +31,10 @@ class BASE_EXPORT PowerMonitorSource {
   // Is the computer currently on battery power. Can be called on any thread.
   bool IsOnBatteryPower();
 
+  // Reads the current DeviceThermalState, if available on the platform.
+  // Otherwise, returns kUnknown.
+  virtual PowerObserver::DeviceThermalState GetCurrentThermalState();
+
   static const char* DeviceThermalStateToString(
       PowerObserver::DeviceThermalState state);
 

base/power_monitor/power_monitor_unittest.cc

@@ -102,6 +102,7 @@ TEST_F(PowerMonitorTest, ThermalThrottling) {
 
   for (const auto state : kThermalStates) {
     source()->GenerateThermalThrottlingEvent(state);
+    EXPECT_EQ(state, source()->GetCurrentThermalState());
     EXPECT_EQ(observer.last_thermal_state(), state);
   }
 

base/power_monitor/thermal_state_observer_mac.h

@@ -14,9 +14,9 @@
 
 namespace base {
 
-// This class is used to listen for the thermal state change notification from
-// NSProcessInfoThermalStateDidChangeNotification via a fully owned
-// ThermalStateObserverDelegate, routing the notification to PowerMonitorSource.
+// This class is used to listen for the thermal state change notification
+// NSProcessInfoThermalStateDidChangeNotification, routing it to
+// PowerMonitorSource.
 class BASE_EXPORT ThermalStateObserverMac {
  public:
   using StateUpdateCallback =
@@ -25,6 +25,8 @@ class BASE_EXPORT ThermalStateObserverMac {
   explicit ThermalStateObserverMac(StateUpdateCallback state_update_callback);
   ~ThermalStateObserverMac();
 
+  PowerObserver::DeviceThermalState GetCurrentThermalState();
+
  private:
   FRIEND_TEST_ALL_PREFIXES(ThermalStateObserverMacTest, StateChange);
   PowerObserver::DeviceThermalState state_for_testing_ =

base/power_monitor/thermal_state_observer_mac.mm

@@ -63,4 +63,13 @@ ThermalStateObserverMac::~ThermalStateObserverMac() {
   [[NSNotificationCenter defaultCenter]
       removeObserver:thermal_state_update_observer_];
 }
+
+PowerObserver::DeviceThermalState
+ThermalStateObserverMac::GetCurrentThermalState() NS_AVAILABLE_MAC(10_10_3) {
+  if (state_for_testing_ != PowerObserver::DeviceThermalState::kUnknown)
+    return state_for_testing_;
+  NSProcessInfoThermalState nsinfo_state =
+      [[NSProcessInfo processInfo] thermalState];
+  return NSProcessInfoThermalStateToDeviceThermalState(nsinfo_state);
+}
 }

base/test/power_monitor_test_base.cc

@@ -11,14 +11,18 @@
 
 namespace base {
 
-PowerMonitorTestSource::PowerMonitorTestSource()
-    : test_on_battery_power_(false) {
+PowerMonitorTestSource::PowerMonitorTestSource() {
   DCHECK(MessageLoopCurrent::Get())
       << "PowerMonitorTestSource requires a MessageLoop.";
 }
 
 PowerMonitorTestSource::~PowerMonitorTestSource() = default;
 
+PowerObserver::DeviceThermalState
+PowerMonitorTestSource::GetCurrentThermalState() {
+  return current_thermal_state_;
+}
+
 void PowerMonitorTestSource::GeneratePowerStateEvent(bool on_battery_power) {
   test_on_battery_power_ = on_battery_power;
   ProcessPowerEvent(POWER_STATE_EVENT);
@@ -42,6 +46,7 @@ bool PowerMonitorTestSource::IsOnBatteryPowerImpl() {
 void PowerMonitorTestSource::GenerateThermalThrottlingEvent(
     PowerObserver::DeviceThermalState new_thermal_state) {
   ProcessThermalEvent(new_thermal_state);
+  current_thermal_state_ = new_thermal_state;
   RunLoop().RunUntilIdle();
 }
 

base/test/power_monitor_test_base.h

@@ -14,6 +14,7 @@ class PowerMonitorTestSource : public PowerMonitorSource {
  public:
   PowerMonitorTestSource();
   ~PowerMonitorTestSource() override;
+  PowerObserver::DeviceThermalState GetCurrentThermalState() override;
 
   void GeneratePowerStateEvent(bool on_battery_power);
   void GenerateSuspendEvent();
@@ -24,7 +25,9 @@ class PowerMonitorTestSource : public PowerMonitorSource {
  protected:
   bool IsOnBatteryPowerImpl() override;
 
-  bool test_on_battery_power_;
+  bool test_on_battery_power_ = false;
+  PowerObserver::DeviceThermalState current_thermal_state_ =
+      PowerObserver::DeviceThermalState::kUnknown;
 };
 
 class PowerMonitorTestObserver : public PowerObserver {