[On-device adaptive brightness] Remove the need of VerifyAlsConfig from AlsReaderImpl

AlsReaderImpl previously checked number of ALS config steps to determine if a
device should be supported. We now use ModelConfigLoader to load model config
that will tell us if a device is supported, hence this cl removes config
verification from AlsReaderImpl.

Bug: 881215
Change-Id: I273a1b1b518970ae49632622acb25a8cfd69c5f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1505747
Commit-Queue: Jia Meng <jiameng@chromium.org>
Reviewed-by: Michael Martis <martis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638524}

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

@@ -41,32 +41,6 @@ bool IsAlsEnabled() {
   return exit_code == 0;
 }
 
-// Returns whether the ALS step config is what we need. This function is only
-// called if an ALS is enabled. This should run in another thread to be
-// non-blocking to the main thread.
-// TODO(jiameng): we assume one specific device now, and only check if the
-// number of steps is 7.
-bool VerifyAlsConfig() {
-  DCHECK(!content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
-  base::CommandLine command_line{
-      base::FilePath(FILE_PATH_LITERAL("check_powerd_config"))};
-  command_line.AppendArg("--internal_backlight_ambient_light_steps");
-  int exit_code = 0;
-  std::string output;
-  const bool result =
-      base::GetAppOutputWithExitCode(command_line, &output, &exit_code);
-
-  if (!result || exit_code != 0) {
-    LOG(ERROR) << "Cannot run check_powerd_config "
-                  "--internal_backlight_ambient_light_steps";
-    return false;
-  }
-
-  const std::vector<base::StringPiece> num_steps = base::SplitStringPiece(
-      output, "\n", base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
-  return num_steps.size() == 7;
-}
-
 // Returns ALS path. This should run in another thread to be non-blocking to the
 // main thread.
 std::string GetAlsPath() {
@@ -158,7 +132,6 @@ void AlsReaderImpl::InitForTesting(const base::FilePath& ambient_light_path) {
 }
 
 void AlsReaderImpl::FailForTesting() {
-  OnAlsConfigCheckDone(false);
   OnAlsEnableCheckDone(false);
   for (int i = 0; i <= kMaxInitialAttempts; i++)
     OnAlsPathReadAttempted("");
@@ -172,20 +145,6 @@ void AlsReaderImpl::OnAlsEnableCheckDone(const bool is_enabled) {
     return;
   }
 
-  base::PostTaskAndReplyWithResult(
-      blocking_task_runner_.get(), FROM_HERE, base::BindOnce(&VerifyAlsConfig),
-      base::BindOnce(&AlsReaderImpl::OnAlsConfigCheckDone,
-                     weak_ptr_factory_.GetWeakPtr()));
-}
-
-void AlsReaderImpl::OnAlsConfigCheckDone(const bool is_config_valid) {
-  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-  if (!is_config_valid) {
-    status_ = AlsInitStatus::kIncorrectConfig;
-    OnInitializationComplete();
-    return;
-  }
-
   RetryAlsPath();
 }
 

chrome/browser/chromeos/power/auto_screen_brightness/als_reader_impl.h

@@ -66,9 +66,6 @@ class AlsReaderImpl : public AlsReader {
   // Called when we've checked whether ALS is enabled.
   void OnAlsEnableCheckDone(bool is_enabled);
 
-  // Called when we've checked whether ALS config is valid.
-  void OnAlsConfigCheckDone(bool is_config_valid);
-
   // Called when we've tried to read ALS path. If |path| is empty, it would
   // reschedule another attempt up to |kMaxInitialAttempts|.
   void OnAlsPathReadAttempted(const std::string& path);

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

@@ -108,13 +108,10 @@ TEST_F(AlsReaderImplTest, ErrorMetrics) {
   als_reader_.FailForTesting();
   histogram_tester_.ExpectBucketCount(
       histogram, static_cast<int>(AlsReader::AlsInitStatus::kDisabled), 1);
-  histogram_tester_.ExpectBucketCount(
-      histogram, static_cast<int>(AlsReader::AlsInitStatus::kIncorrectConfig),
-      1);
   histogram_tester_.ExpectBucketCount(
       histogram, static_cast<int>(AlsReader::AlsInitStatus::kMissingPath), 1);
-  // Expect 3 errors from above + 1 success from before |FailForTesting|.
-  histogram_tester_.ExpectTotalCount(histogram, 4);
+  // Expect 2 errors from above + 1 success from before |FailForTesting|.
+  histogram_tester_.ExpectTotalCount(histogram, 3);
 }
 
 TEST_F(AlsReaderImplTest, OneAlsValue) {