Oilpan: Query stack frame register instead of manual bookkeeping

Source/platform/heap/StackFrameDepth.cpp

Index: Source/platform/heap/StackFrameDepth.cpp
diff --git a/Source/platform/heap/StackFrameDepth.cpp b/Source/platform/heap/StackFrameDepth.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..55f710fe0a02596786ac64c7d85a8b86187177b7
--- /dev/null
+++ b/Source/platform/heap/StackFrameDepth.cpp
@@ -0,0 +1,26 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "platform/heap/StackFrameDepth.h"
+
+namespace blink {
+
+void StackFrameDepth::configureLimit()
+{
+    if (!isEstimationSupported()) {
+        m_depth = 0;
+        return;
+    }
+
+    // Allocate a large object in stack and query stack frame pointer after it.
+    const size_t kTypicalNumberOfPointerPerFrame = 4; // Return address + 3 local variables/argument
+    char dummy[kMaxDepth * kTypicalNumberOfPointerPerFrame * sizeof(void*)];
+    m_safeStackFrame = StackFrameDepth::estimateCurrentStackFrame();
+
+    // Assert that the stack frame can be used.
+    dummy[sizeof(dummy)-1] = 0;
+}
+
+} // namespace blink