Introduce a RandonNumberGenerator class. Refactor the random/private_random uses in Isolate/Context.

src/platform-cygwin.cc

Index: src/platform-cygwin.cc
diff --git a/src/platform-cygwin.cc b/src/platform-cygwin.cc
index 6b41417a0650c525e32f36de2509270d2c47241d..d7dcaf0569692a8b030c15d436c7bc4b560b1423 100644
--- a/src/platform-cygwin.cc
+++ b/src/platform-cygwin.cc
@@ -236,8 +236,9 @@ static void* GetRandomAddr() {
     static const intptr_t kAllocationRandomAddressMin = 0x04000000;
     static const intptr_t kAllocationRandomAddressMax = 0x3FFF0000;
 #endif
-    uintptr_t address = (V8::RandomPrivate(isolate) << kPageSizeBits)
-        | kAllocationRandomAddressMin;
+    uintptr_t address =
+        (isolate->random_number_generator()->NextInt() << kPageSizeBits) |
+        kAllocationRandomAddressMin;
     address &= kAllocationRandomAddressMax;
     return reinterpret_cast<void *>(address);
   }
@@ -366,16 +367,4 @@ bool VirtualMemory::HasLazyCommits() {
   return false;
 }
 
-
-void OS::SetUp() {
-  // Seed the random number generator.
-  // Convert the current time to a 64-bit integer first, before converting it
-  // to an unsigned. Going directly can cause an overflow and the seed to be
-  // set to all ones. The seed will be identical for different instances that
-  // call this setup code within the same millisecond.
-  uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis());
-  srandom(static_cast<unsigned int>(seed));
-}
-
-
 } }  // namespace v8::internal