chromeos/dbus: Add ambient color temperature signal to PowerManagerClient

This CL adds support for dbus "AmbientColorTemperatureChanged" signal.
A new method AmbientColorChanged is added to PowerManagerClient
and it will be called every time powerd emits a new ambient color
temperature.

A prototpe using the new signal can be found here: crrev.com/c/1883289

Bug: b/138731765
Test: chromeos_unittests --gtest_filter=PowerManagerClientTest.ChangeAmbientColorTemperature

Change-Id: Idf6462e90f4c378cd03dfd131434e045748deaf6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1900432
Commit-Queue: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713622}

chromeos/dbus/power/power_manager_client.cc

@@ -178,6 +178,8 @@ class PowerManagerClientImpl : public PowerManagerClient {
     const std::map<const char*, SignalMethod> kSignalMethods = {
         {power_manager::kScreenBrightnessChangedSignal,
          &PowerManagerClientImpl::ScreenBrightnessChangedReceived},
+        {power_manager::kAmbientColorTemperatureChangedSignal,
+         &PowerManagerClientImpl::AmbientColorTemperatureChangedReceived},
         {power_manager::kKeyboardBrightnessChangedSignal,
          &PowerManagerClientImpl::KeyboardBrightnessChangedReceived},
         {power_manager::kScreenIdleStateChangedSignal,
@@ -617,6 +619,20 @@ class PowerManagerClientImpl : public PowerManagerClient {
       observer.ScreenBrightnessChanged(proto);
   }
 
+  void AmbientColorTemperatureChangedReceived(dbus::Signal* signal) {
+    dbus::MessageReader reader(signal);
+    int32_t color_temperature = 0;
+    if (!reader.PopInt32(&color_temperature)) {
+      POWER_LOG(ERROR) << "Unable to decode read ambient color from "
+                       << power_manager::kAmbientColorTemperatureChangedSignal
+                       << " signal";
+      return;
+    }
+
+    for (auto& observer : observers_)
+      observer.AmbientColorChanged(color_temperature);
+  }
+
   void KeyboardBrightnessChangedReceived(dbus::Signal* signal) {
     dbus::MessageReader reader(signal);
     power_manager::BacklightBrightnessChange proto;

chromeos/dbus/power/power_manager_client.h

@@ -82,6 +82,9 @@ class COMPONENT_EXPORT(DBUS_POWER) PowerManagerClient {
     virtual void ScreenBrightnessChanged(
         const power_manager::BacklightBrightnessChange& change) {}
 
+    // Called when the ambient light changed.
+    virtual void AmbientColorChanged(const int32_t color_temperature) {}
+
     // Called when the keyboard brightness is changed.
     virtual void KeyboardBrightnessChanged(
         const power_manager::BacklightBrightnessChange& change) {}

chromeos/dbus/power/power_manager_client_unittest.cc

@@ -96,6 +96,9 @@ class TestObserver : public PowerManagerClient::Observer {
   const base::UnguessableToken& block_suspend_token() const {
     return block_suspend_token_;
   }
+  int32_t ambient_color_temperature() const {
+    return ambient_color_temperature_;
+  }
 
   void set_should_block_suspend(bool take_callback) {
     should_block_suspend_ = take_callback;
@@ -135,6 +138,9 @@ class TestObserver : public PowerManagerClient::Observer {
     if (run_unblock_suspend_immediately_)
       CHECK(UnblockSuspend());
   }
+  void AmbientColorChanged(const int32_t color_temperature) override {
+    ambient_color_temperature_ = color_temperature;
+  }
 
  private:
   PowerManagerClient* client_;  // Not owned.
@@ -157,6 +163,8 @@ class TestObserver : public PowerManagerClient::Observer {
   // When non-empty, the token for the outstanding block-suspend registration.
   base::UnguessableToken block_suspend_token_;
 
+  // Ambient color temperature
+  int32_t ambient_color_temperature_ = 0;
   DISALLOW_COPY_AND_ASSIGN(TestObserver);
 };
 
@@ -592,4 +600,17 @@ TEST_F(PowerManagerClientTest, SyncCallbackWithMultipleObservers) {
   EmitSuspendDoneSignal(kSuspendId);
 }
 
+// Tests that observers are notified about changes in ambient color temperature.
+TEST_F(PowerManagerClientTest, ChangeAmbientColorTemperature) {
+  TestObserver observer(client_);
+
+  constexpr int32_t kTemperature = 6500;
+  dbus::Signal signal(kInterface,
+                      power_manager::kAmbientColorTemperatureChangedSignal);
+  dbus::MessageWriter(&signal).AppendInt32(kTemperature);
+  EmitSignal(&signal);
+
+  EXPECT_EQ(kTemperature, observer.ambient_color_temperature());
+}
+
 }  // namespace chromeos