Revert "[base] Ensure that tests don't change the thread priority."

This reverts commit a4dd23f.

Reason for revert: https://bugs.chromium.org/p/chromium/issues/detail?id=1004879

Original change's description:
> [base] Ensure that tests don't change the thread priority.
> 
> This CL verifies that the thread priority is normal when a test process
> is launched and before/after each test. The goal is to avoid having
> tests that assume they run at normal priority be disabled because of
> other misbehaving tests (e.g. https://crbug.com/931706).
> 
> Bug: 931706
> Change-Id: I5ca18b87720b5305285be481f7b60ff5c941a324
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1804786
> Commit-Queue: Scott Violet <sky@chromium.org>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Reviewed-by: Scott Violet <sky@chromium.org>
> Reviewed-by: Gabriel Charette <gab@chromium.org>
> Auto-Submit: François Doray <fdoray@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#697261}

TBR=sky@chromium.org,gab@chromium.org,thakis@chromium.org,fdoray@chromium.org,michaelpg@chromium.org,eseckler@chromium.org

Change-Id: I900562585a34cd92a4f49a215d7c323706ce468d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 931706,1004879
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1808814
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697316}

ash/shell/content/test/ash_content_perf_test_launcher.cc

@@ -34,10 +34,9 @@ class AshContentTestSuite : public content::ContentTestSuiteBase {
  protected:
   // content::ContentTestSuiteBase:
   void Initialize() override {
-    // Browser tests are expected not to tear-down various globals and may
-    // complete with the thread priority being above NORMAL.
+    // Browser tests are expected not to tear-down various globals. (Must run
+    // before the base class is initialized.)
     base::TestSuite::DisableCheckForLeakedGlobals();
-    base::TestSuite::DisableCheckForThreadPriorityAtTestEnd();
     ContentTestSuiteBase::Initialize();
     ui_controls::InstallUIControlsAura(ash::test::CreateAshUIControls());
   }

base/test/test_suite.cc

@@ -37,7 +37,6 @@
 #include "base/test/multiprocess_test.h"
 #include "base/test/test_switches.h"
 #include "base/test/test_timeouts.h"
-#include "base/threading/platform_thread.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ -189,31 +188,6 @@ class CheckProcessPriority : public testing::EmptyTestEventListener {
 };
 #endif  // !defined(OS_IOS)
 
-class CheckThreadPriority : public testing::EmptyTestEventListener {
- public:
-  CheckThreadPriority(bool check_thread_priority_at_test_end)
-      : check_thread_priority_at_test_end_(check_thread_priority_at_test_end) {
-    CHECK_EQ(base::PlatformThread::GetCurrentThreadPriority(),
-             base::ThreadPriority::NORMAL);
-  }
-
-  void OnTestStart(const testing::TestInfo& test) override {
-    EXPECT_EQ(base::PlatformThread::GetCurrentThreadPriority(),
-              base::ThreadPriority::NORMAL);
-  }
-  void OnTestEnd(const testing::TestInfo& test) override {
-    if (check_thread_priority_at_test_end_) {
-      EXPECT_EQ(base::PlatformThread::GetCurrentThreadPriority(),
-                base::ThreadPriority::NORMAL);
-    }
-  }
-
- private:
-  const bool check_thread_priority_at_test_end_;
-
-  DISALLOW_COPY_AND_ASSIGN(CheckThreadPriority);
-};
-
 const std::string& GetProfileName() {
   static const NoDestructor<std::string> profile_name([]() {
     const CommandLine& command_line = *CommandLine::ForCurrentProcess();
@@ -407,11 +381,6 @@ void TestSuite::DisableCheckForProcessPriority() {
   check_for_process_priority_ = false;
 }
 
-void TestSuite::DisableCheckForThreadPriorityAtTestEnd() {
-  DCHECK(!is_initialized_);
-  check_for_thread_priority_at_test_end_ = false;
-}
-
 void TestSuite::UnitTestAssertHandler(const char* file,
                                       int line,
                                       const StringPiece summary,
@@ -602,8 +571,6 @@ void TestSuite::Initialize() {
   if (check_for_process_priority_)
     listeners.Append(new CheckProcessPriority);
 #endif
-  listeners.Append(
-      new CheckThreadPriority(check_for_thread_priority_at_test_end_));
 
   AddTestLauncherResultPrinter();
 

base/test/test_suite.h

@@ -46,10 +46,6 @@ class TestSuite {
   // Disables checks for process priority. Most tests should not use this.
   void DisableCheckForProcessPriority();
 
-  // Disables checks for thread priority at test end. This may be used for tests
-  // that each run in their own process.
-  void DisableCheckForThreadPriorityAtTestEnd();
-
   // Disables checks for certain global objects being leaked across tests.
   void DisableCheckForLeakedGlobals();
 
@@ -98,7 +94,6 @@ class TestSuite {
 
   bool check_for_leaked_globals_ = true;
   bool check_for_process_priority_ = true;
-  bool check_for_thread_priority_at_test_end_ = true;
 
   bool is_initialized_ = false;
 

chrome/test/base/browser_tests_main_chromeos.cc

@@ -30,10 +30,8 @@ class BrowserTestSuiteRunnerChromeOS : public ChromeTestSuiteRunner {
  public:
   int RunTestSuite(int argc, char** argv) override {
     BrowserTestSuiteChromeOS test_suite(argc, argv);
-    // Browser tests are expected not to tear-down various globals and may
-    // complete with the thread priority being above NORMAL.
+    // Browser tests are expected not to tear-down various globals.
     test_suite.DisableCheckForLeakedGlobals();
-    test_suite.DisableCheckForThreadPriorityAtTestEnd();
     return test_suite.Run();
   }
 };

chrome/test/base/chrome_test_launcher.cc

@@ -76,10 +76,8 @@ ChromeTestSuiteRunner::~ChromeTestSuiteRunner() {}
 
 int ChromeTestSuiteRunner::RunTestSuite(int argc, char** argv) {
   ChromeTestSuite test_suite(argc, argv);
-  // Browser tests are expected not to tear-down various globals and may
-  // complete with the thread priority being above NORMAL.
+  // Browser tests are expected not to tear-down various globals.
   test_suite.DisableCheckForLeakedGlobals();
-  test_suite.DisableCheckForThreadPriorityAtTestEnd();
 #if defined(OS_ANDROID)
   // Android browser tests run child processes as threads instead.
   content::ContentTestSuiteBase::RegisterInProcessThreads();

chrome/test/base/interactive_ui_tests_main.cc

@@ -41,10 +41,8 @@ class InteractiveUITestSuite : public ChromeTestSuite {
  protected:
   // ChromeTestSuite overrides:
   void Initialize() override {
-    // Browser tests are expected not to tear-down various globals and may
-    // complete with the thread priority being above NORMAL.
+    // Browser tests are expected not to tear-down various globals.
     base::TestSuite::DisableCheckForLeakedGlobals();
-    base::TestSuite::DisableCheckForThreadPriorityAtTestEnd();
 
     ChromeTestSuite::Initialize();
 

chromecast/app/cast_test_launcher.cc

@@ -23,10 +23,8 @@ class CastTestLauncherDelegate : public content::TestLauncherDelegate {
 
   int RunTestSuite(int argc, char** argv) override {
     base::TestSuite test_suite(argc, argv);
-    // Browser tests are expected not to tear-down various globals and may
-    // complete with the thread priority being above NORMAL.
+    // Browser tests are expected not to tear-down various globals.
     test_suite.DisableCheckForLeakedGlobals();
-    test_suite.DisableCheckForThreadPriorityAtTestEnd();
     return test_suite.Run();
   }
 

content/test/content_test_launcher.cc

@@ -39,10 +39,9 @@ class ContentBrowserTestSuite : public ContentTestSuiteBase {
 
  protected:
   void Initialize() override {
-    // Browser tests are expected not to tear-down various globals and may
-    // complete with the thread priority being above NORMAL.
+    // Browser tests are expected not to tear-down various globals. (Must run
+    // before the base class is initialized.)
     base::TestSuite::DisableCheckForLeakedGlobals();
-    base::TestSuite::DisableCheckForThreadPriorityAtTestEnd();
 
     ContentTestSuiteBase::Initialize();
 

extensions/shell/test/shell_test_launcher_delegate.cc

@@ -13,10 +13,8 @@ namespace extensions {
 
 int AppShellTestLauncherDelegate::RunTestSuite(int argc, char** argv) {
   base::TestSuite test_suite(argc, argv);
-  // Browser tests are expected not to tear-down various globals and may
-  // complete with the thread priority being above NORMAL.
+  // Browser tests are expected not to tear-down various globals.
   test_suite.DisableCheckForLeakedGlobals();
-  test_suite.DisableCheckForThreadPriorityAtTestEnd();
   return test_suite.Run();
 }
 

fuchsia/engine/test/web_engine_test_launcher.cc

@@ -25,10 +25,8 @@ class WebEngineTestLauncherDelegate : public content::TestLauncherDelegate {
   // content::TestLauncherDelegate implementation:
   int RunTestSuite(int argc, char** argv) override {
     base::TestSuite test_suite(argc, argv);
-    // Browser tests are expected not to tear-down various globals and may
-    // complete with the thread priority being above NORMAL.
+    // Browser tests are expected not to tear-down various globals.
     test_suite.DisableCheckForLeakedGlobals();
-    test_suite.DisableCheckForThreadPriorityAtTestEnd();
     return test_suite.Run();
   }
 

headless/test/headless_test_launcher.cc

@@ -41,10 +41,8 @@ class HeadlessTestLauncherDelegate : public content::TestLauncherDelegate {
   // content::TestLauncherDelegate implementation:
   int RunTestSuite(int argc, char** argv) override {
     base::TestSuite test_suite(argc, argv);
-    // Browser tests are expected not to tear-down various globals and may
-    // complete with the thread priority being above NORMAL.
+    // Browser tests are expected not to tear-down various globals.
     test_suite.DisableCheckForLeakedGlobals();
-    test_suite.DisableCheckForThreadPriorityAtTestEnd();
     return test_suite.Run();
   }