Use actual incremental marking throughput in IdleNotification to estimate marking step size.

test/heap-unittests/heap-unittest.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
+#define __STDC_LIMIT_MACROS
+#include <stdint.h>
+
+#include "src/allocation.h"
+#include "src/heap/gc-idle-time-handler.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace v8 {
 namespace internal {
 
-TEST(HeapTest, Dummy) {
-  EXPECT_FALSE(false);
-  EXPECT_TRUE(true);
+TEST(EstimateMarkingStepSizeTest, EstimateMarkingStepSizeInitial) {
+  intptr_t step_size = GCIdleTimeHandler::EstimateMarkingStepSize(1, 0);
+  EXPECT_EQ(step_size, static_cast<intptr_t>(
+                           GCIdleTimeHandler::kInitialConservativeMarkingSpeed *
+                           GCIdleTimeHandler::kConservativeTimeRatio));
+}
+
+
+TEST(EstimateMarkingStepSizeTest, EstimateMarkingStepSizeNonZero) {
+  intptr_t marking_speed_in_bytes_per_millisecond = 100;
+  intptr_t step_size = GCIdleTimeHandler::EstimateMarkingStepSize(
+      1, marking_speed_in_bytes_per_millisecond);
+  EXPECT_EQ(step_size,
+            static_cast<intptr_t>(marking_speed_in_bytes_per_millisecond *
+                                  GCIdleTimeHandler::kConservativeTimeRatio));
+}
+
+
+TEST(EstimateMarkingStepSizeTest, EstimateMarkingStepSizeOverflow1) {
+  intptr_t step_size =
+      GCIdleTimeHandler::EstimateMarkingStepSize(10, INTPTR_MAX);
+  EXPECT_EQ(step_size, INTPTR_MAX);
+}
+
+
+TEST(EstimateMarkingStepSizeTest, EstimateMarkingStepSizeOverflow2) {
+  intptr_t step_size = GCIdleTimeHandler::EstimateMarkingStepSize(INT_MAX, 10);
+  EXPECT_EQ(step_size, INTPTR_MAX);
 }
 
 }  // namespace internal
 }  // namespace v8