Synchronize with r15594.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 638968506d1c7d159c44bef46fd03a34b0aa8808..980c039792652b442045708b8e2c9d12502594af 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -781,10 +781,12 @@ void MarkCompactCollector::CollectEvacuationCandidates(PagedSpace* space) {
   }
 
   if (FLAG_trace_fragmentation && mode == REDUCE_MEMORY_FOOTPRINT) {
-    PrintF("Estimated over reserved memory: %.1f / %.1f MB (threshold %d)\n",
+    PrintF("Estimated over reserved memory: %.1f / %.1f MB (threshold %d), "
+           "evacuation candidate limit: %d\n",
            static_cast<double>(over_reserved) / MB,
            static_cast<double>(reserved) / MB,
-           static_cast<int>(kFreenessThreshold));
+           static_cast<int>(kFreenessThreshold),
+           max_evacuation_candidates);
   }
 
   intptr_t estimated_release = 0;
@@ -811,7 +813,7 @@ void MarkCompactCollector::CollectEvacuationCandidates(PagedSpace* space) {
       if ((counter & 1) == (page_number & 1)) fragmentation = 1;
     } else if (mode == REDUCE_MEMORY_FOOTPRINT) {
       // Don't try to release too many pages.
-      if (estimated_release >= ((over_reserved * 3) / 4)) {
+      if (estimated_release >= over_reserved) {
         continue;
       }
 
@@ -828,7 +830,7 @@ void MarkCompactCollector::CollectEvacuationCandidates(PagedSpace* space) {
       int free_pct = static_cast<int>(free_bytes * 100) / p->area_size();
 
       if (free_pct >= kFreenessThreshold) {
-        estimated_release += 2 * p->area_size() - free_bytes;
+        estimated_release += free_bytes;
         fragmentation = free_pct;
       } else {
         fragmentation = 0;
@@ -1929,7 +1931,8 @@ static void DiscoverGreyObjectsWithIterator(Heap* heap,
 static inline int MarkWordToObjectStarts(uint32_t mark_bits, int* starts);
 
 
-static void DiscoverGreyObjectsOnPage(MarkingDeque* marking_deque, Page* p) {
+static void DiscoverGreyObjectsOnPage(MarkingDeque* marking_deque,
+                                      MemoryChunk* p) {
   ASSERT(!marking_deque->IsFull());
   ASSERT(strcmp(Marking::kWhiteBitPattern, "00") == 0);
   ASSERT(strcmp(Marking::kBlackBitPattern, "10") == 0);
@@ -2003,6 +2006,18 @@ static void DiscoverGreyObjectsInSpace(Heap* heap,
 }
 
 
+static void DiscoverGreyObjectsInNewSpace(Heap* heap,
+                                          MarkingDeque* marking_deque) {
+  NewSpace* space = heap->new_space();
+  NewSpacePageIterator it(space->bottom(), space->top());
+  while (it.has_next()) {
+    NewSpacePage* page = it.next();
+    DiscoverGreyObjectsOnPage(marking_deque, page);
+    if (marking_deque->IsFull()) return;
+  }
+}
+
+
 bool MarkCompactCollector::IsUnmarkedHeapObject(Object** p) {
   Object* o = *p;
   if (!o->IsHeapObject()) return false;
@@ -2109,8 +2124,7 @@ void MarkCompactCollector::EmptyMarkingDeque() {
 void MarkCompactCollector::RefillMarkingDeque() {
   ASSERT(marking_deque_.overflowed());
 
-  SemiSpaceIterator new_it(heap()->new_space());
-  DiscoverGreyObjectsWithIterator(heap(), &marking_deque_, &new_it);
+  DiscoverGreyObjectsInNewSpace(heap(), &marking_deque_);
   if (marking_deque_.IsFull()) return;
 
   DiscoverGreyObjectsInSpace(heap(),