[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}

ash/shell/content/test/ash_content_perf_test_launcher.cc

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

base/test/test_suite.cc

@@ -37,6 +37,7 @@
 #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"
@@ -188,6 +189,31 @@ 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();
@@ -381,6 +407,11 @@ 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,
@@ -571,6 +602,8 @@ 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

@@ -46,6 +46,10 @@ 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();
 
@@ -94,6 +98,7 @@ 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

@@ -30,8 +30,10 @@ 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.
+    // Browser tests are expected not to tear-down various globals and may
+    // complete with the thread priority being above NORMAL.
     test_suite.DisableCheckForLeakedGlobals();
+    test_suite.DisableCheckForThreadPriorityAtTestEnd();
     return test_suite.Run();
   }
 };

chrome/test/base/chrome_test_launcher.cc

@@ -76,8 +76,10 @@ ChromeTestSuiteRunner::~ChromeTestSuiteRunner() {}
 
 int ChromeTestSuiteRunner::RunTestSuite(int argc, char** argv) {
   ChromeTestSuite test_suite(argc, argv);
-  // Browser tests are expected not to tear-down various globals.
+  // Browser tests are expected not to tear-down various globals and may
+  // complete with the thread priority being above NORMAL.
   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

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

chromecast/app/cast_test_launcher.cc

@@ -23,8 +23,10 @@ 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.
+    // Browser tests are expected not to tear-down various globals and may
+    // complete with the thread priority being above NORMAL.
     test_suite.DisableCheckForLeakedGlobals();
+    test_suite.DisableCheckForThreadPriorityAtTestEnd();
     return test_suite.Run();
   }
 

content/test/content_test_launcher.cc

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

extensions/shell/test/shell_test_launcher_delegate.cc

@@ -13,8 +13,10 @@ 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.
+  // Browser tests are expected not to tear-down various globals and may
+  // complete with the thread priority being above NORMAL.
   test_suite.DisableCheckForLeakedGlobals();
+  test_suite.DisableCheckForThreadPriorityAtTestEnd();
   return test_suite.Run();
 }
 

fuchsia/engine/test/web_engine_test_launcher.cc

@@ -25,8 +25,10 @@ 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.
+    // Browser tests are expected not to tear-down various globals and may
+    // complete with the thread priority being above NORMAL.
     test_suite.DisableCheckForLeakedGlobals();
+    test_suite.DisableCheckForThreadPriorityAtTestEnd();
     return test_suite.Run();
   }
 

headless/test/headless_test_launcher.cc

@@ -41,8 +41,10 @@ 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.
+    // Browser tests are expected not to tear-down various globals and may
+    // complete with the thread priority being above NORMAL.
     test_suite.DisableCheckForLeakedGlobals();
+    test_suite.DisableCheckForThreadPriorityAtTestEnd();
     return test_suite.Run();
   }