Oilpan: Don't send a BlinkGC.CompleteSweep UMA from non-main threads

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 04ff08f580f321ce727fcdcdd639024818d8d64c..271e32ac6b65388478517513640f291472469c98 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.cpp
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
@@ -1114,11 +1114,12 @@ void ThreadState::completeSweep()
             m_heaps[i]->completeSweep();
 
         double timeForCompleteSweep = WTF::currentTimeMS() - startTime;
-        Platform::current()->histogramCustomCounts("BlinkGC.CompleteSweep", timeForCompleteSweep, 0, 10 * 1000, 50);
         accumulateSweepingTime(timeForCompleteSweep);
 
-        if (isMainThread())
+        if (isMainThread()) {
             ScriptForbiddenScope::exit();
+            Platform::current()->histogramCustomCounts("BlinkGC.CompleteSweep", timeForCompleteSweep, 1, 10 * 1000, 50);
+        }
     }
 
     postSweep();