Revert "[Sheriff] Disable flaky test ProcessTests"

This reverts commit aa165da6.

Reason for revert: The tests should no longer fail with the
checks added in https://chromium-review.googlesource.com/c/chromium/src/+/1790331.

Original change's description:
> [Sheriff] Disable flaky test ProcessTests
> 
> Disable ProcessTest.SetProcessBackgroundedSelf and
> ProcessTest.SetProcessBackgrounded on Windows.
> 
> Bug: 931721
> TBR=fdoray@chromium.org
> 
> Change-Id: Ie5b2882c1d9d39ba5527d610c2a56223e01e74ed
> Reviewed-on: https://chromium-review.googlesource.com/c/1470996
> Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
> Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#631862}

TBR=rdevlin.cronin@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 931721
Change-Id: Ia2017959c57a9acfb58bbb435a7c91154def29be
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1793527Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Auto-Submit: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695130}

base/process/process_unittest.cc

@@ -271,13 +271,7 @@ TEST_F(ProcessTest, WaitForExitWithTimeout) {
 // backgrounding and restoring.
 // Note: a platform may not be willing or able to lower the priority of
 // a process. The calls to SetProcessBackground should be noops then.
-// Flaky on Windows: https://crbug.com/931721.
-#if defined(OS_WIN)
-#define MAYBE_SetProcessBackgrounded DISABLED_SetProcessBackgrounded
-#else
-#define MAYBE_SetProcessBackgrounded SetProcessBackgrounded
-#endif
-TEST_F(ProcessTest, MAYBE_SetProcessBackgrounded) {
+TEST_F(ProcessTest, SetProcessBackgrounded) {
   if (!Process::CanBackgroundProcesses())
     return;
   Process process(SpawnChild("SimpleChildProcess"));
@@ -305,15 +299,9 @@ TEST_F(ProcessTest, MAYBE_SetProcessBackgrounded) {
   EXPECT_EQ(old_priority, new_priority);
 }
 
-// Flaky on Windows: https://crbug.com/931721.
-#if defined(OS_WIN)
-#define MAYBE_SetProcessBackgroundedSelf DISABLED_SetProcessBackgroundedSelf
-#else
-#define MAYBE_SetProcessBackgroundedSelf SetProcessBackgroundedSelf
-#endif
 // Same as SetProcessBackgrounded but to this very process. It uses
 // a different code path at least for Windows.
-TEST_F(ProcessTest, MAYBE_SetProcessBackgroundedSelf) {
+TEST_F(ProcessTest, SetProcessBackgroundedSelf) {
   if (!Process::CanBackgroundProcesses())
     return;
   Process process = Process::Current();