[On-device adaptive brightness] More logging for sys report

This cl adds more logging into sys report so that we can help users
better when they file a bug report.

Bug: 881215
Change-Id: Iea0f1ef052d68ee608f64fed25e1a727b1c50c70
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1871719
Commit-Queue: Jia Meng <jiameng@chromium.org>
Reviewed-by: Charles . <charleszhao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708804}

chrome/browser/chromeos/power/auto_screen_brightness/adapter.cc

@@ -697,8 +697,13 @@ double Adapter::GetBrightnessBasedOnAmbientLogLux(
     double ambient_log_lux) const {
   DCHECK_EQ(adapter_status_, Status::kSuccess);
   // We use the latest curve available.
-  if (model_.personal_curve)
+  if (model_.personal_curve) {
+    VLOG(1) << "ABAdapter using personal curve for brightness change: \n"
+            << model_.personal_curve->ToString();
     return model_.personal_curve->Interpolate(ambient_log_lux);
+  }
+  VLOG(1) << "ABAdapter using global curve for brightness change: \n"
+          << model_.global_curve->ToString();
   return model_.global_curve->Interpolate(ambient_log_lux);
 }
 

chrome/browser/chromeos/power/auto_screen_brightness/gaussian_trainer.cc

@@ -420,12 +420,16 @@ TrainingResult GaussianTrainer::Train(
   if (!need_to_update_curve_) {
     const double error = CalculateCurveError(data);
     LogModelCurveError(error, false /* model_updated */);
+    VLOG(1) << "ABTrainer training finished without new curve: \n"
+            << current_curve_->ToString();
     return TrainingResult(base::nullopt, error);
   }
 
   current_curve_ = MonotoneCubicSpline::CreateMonotoneCubicSpline(
       ambient_log_lux_, brightness_);
   DCHECK(current_curve_);
+  VLOG(1) << "ABTrainer training finished with new curve: \n"
+          << current_curve_->ToString();
   need_to_update_curve_ = false;
 
   const double error = CalculateCurveError(data);
@@ -452,6 +456,11 @@ void GaussianTrainer::AdjustCurveWithSingleDataPoint(
   const double brightness_global =
       global_curve_->Interpolate(data.ambient_log_lux);
 
+  VLOG(1) << "ABTrainer training data point (global,old,new,log_lux): "
+          << FormatToPrint(brightness_global) << ", "
+          << FormatToPrint(data.brightness_old) << ", "
+          << FormatToPrint(data.brightness_new) << ", " << data.ambient_log_lux;
+
   // Check if this |data| is an outlier and should be ignored. It's an outlier
   // if its original/old brightness is too far off from the brightness as
   // predicted by the global curve. This assumes the global curve is reasonably