Oilpan: Remove synchronous completeSweep() from V8's minor GC prologue

third_party/WebKit/Source/platform/heap/ThreadState.cpp

Index: third_party/WebKit/Source/platform/heap/ThreadState.cpp
diff --git a/third_party/WebKit/Source/platform/heap/ThreadState.cpp b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
index e8672bf1111b4e0078b40fd5993e1a6129d8ad3f..b2da3cbf4ac39f17287ebabe4c3749caeedbbaf5 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.cpp
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
@@ -622,16 +622,17 @@ void ThreadState::scheduleV8FollowupGCIfNeeded(BlinkGC::V8GCType gcType)
     }
 }
 
-void ThreadState::willStartV8GC()
+void ThreadState::willStartV8GC(BlinkGC::V8GCType gcType)
 {
-    // Finish Oilpan's complete sweeping before running a V8 GC.
+    // Finish Oilpan's complete sweeping before running a V8 major GC.
     // This will let the GC collect more V8 objects.
     //
     // TODO(haraken): It's a bit too late for a major GC to schedule
     // completeSweep() here, because gcPrologue for a major GC is called
     // not at the point where the major GC started but at the point where
     // the major GC requests object grouping.
-    completeSweep();
+    if (gcType == BlinkGC::V8MajorGC)
+        completeSweep();
 
     // The fact that the PageNavigation GC is scheduled means that there is
     // a dead frame. In common cases, a sequence of Oilpan's GC => V8 GC =>
@@ -641,6 +642,7 @@ void ThreadState::willStartV8GC()
 #if PRINT_HEAP_STATS
         dataLogF("Scheduled PageNavigationGC\n");
 #endif
+        completeSweep();

[sof, 2016/02/02 08:19:27]

Unnecessary, already done in collectGarbage().

         Heap::collectGarbage(BlinkGC::HeapPointersOnStack, BlinkGC::GCWithSweep, BlinkGC::PageNavigationGC);
     }
 }