[heap] Introduce enum of garbage collection reasons.

test/cctest/heap/test-incremental-marking.cc

Index: test/cctest/heap/test-incremental-marking.cc
diff --git a/test/cctest/heap/test-incremental-marking.cc b/test/cctest/heap/test-incremental-marking.cc
index 59697a94a1fed1b2c695918ab45aaf3af1ec8c34..8d26a3b575c115c5b1c8f27cb6fe7189f52cc991 100644
--- a/test/cctest/heap/test-incremental-marking.cc
+++ b/test/cctest/heap/test-incremental-marking.cc
@@ -122,7 +122,7 @@ TEST(IncrementalMarkingUsingIdleTasks) {
   i::heap::SimulateFullSpace(CcTest::heap()->old_space());
   i::IncrementalMarking* marking = CcTest::heap()->incremental_marking();
   marking->Stop();
-  marking->Start();
+  marking->Start(i::GarbageCollectionReason::kTesting);
   CHECK(platform.PendingIdleTask());
   const double kLongIdleTimeInSeconds = 1;
   const double kShortIdleTimeInSeconds = 0.010;
@@ -145,10 +145,10 @@ TEST(IncrementalMarkingUsingIdleTasksAfterGC) {
   MockPlatform platform(old_platform);
   i::V8::SetPlatformForTesting(&platform);
   i::heap::SimulateFullSpace(CcTest::heap()->old_space());
-  CcTest::heap()->CollectAllGarbage();
+  CcTest::CollectAllGarbage(i::Heap::kFinalizeIncrementalMarkingMask);
   i::IncrementalMarking* marking = CcTest::heap()->incremental_marking();
   marking->Stop();
-  marking->Start();
+  marking->Start(i::GarbageCollectionReason::kTesting);
   CHECK(platform.PendingIdleTask());
   const double kLongIdleTimeInSeconds = 1;
   const double kShortIdleTimeInSeconds = 0.010;
@@ -173,7 +173,7 @@ TEST(IncrementalMarkingUsingDelayedTasks) {
   i::heap::SimulateFullSpace(CcTest::heap()->old_space());
   i::IncrementalMarking* marking = CcTest::heap()->incremental_marking();
   marking->Stop();
-  marking->Start();
+  marking->Start(i::GarbageCollectionReason::kTesting);
   CHECK(platform.PendingIdleTask());
   // The delayed task should be a no-op if the idle task makes progress.
   const int kIgnoredDelayedTaskStepCount = 1000;