Initial GetSample implementation.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 5730fdf8e7fa5bccdf55eaa2de8b45145c606297..b02cbc8db7ba414b48296998e54dce47c37c0589 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -1289,6 +1289,29 @@ class V8_EXPORT StackFrame {
 
 
 /**
+ * Isolate::Getsample collects the current JS execution state as a sample.
+ * A collected sample contains,
+ * - stack       : An array of addresses.
+ *                 One address per stack frame.
+ *                 The address is the instruction pointer,
+ *                 pointing to the instruction which led to the
+ *                 creation of the stack frame.
+ *                 (for example, a function call)
+ * - frames_count: Number of stack frames that were captured.
+ *                 That is, stack[frames_count+i] might contain meaningless
+ *                 addresses for any i >= 0.
+ */
+struct V8_EXPORT Sample {
+  Sample()
+      : frames_count(0) {}
+  static const unsigned kMaxFramesCount = 255;
+
+  void* stack[kMaxFramesCount];  // Call stack.
+  unsigned frames_count;         // Number of captured frames.
+};
+
+
+/**
  * A JSON Parser.
  */
 class V8_EXPORT JSON {
@@ -4208,6 +4231,11 @@ class V8_EXPORT Isolate {
   void GetHeapStatistics(HeapStatistics* heap_statistics);
 
   /**
+   * Get a sample from the isolate.
+   */
+  void GetSample(Sample* sample);
+
+  /**
    * Adjusts the amount of registered external memory. Used to give V8 an
    * indication of the amount of externally allocated memory that is kept alive
    * by JavaScript objects. V8 uses this to decide when to perform global