Initial GetSample implementation.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 73384946ba7d93594fd5c3d78753dfe01c2726f6..fbe3dea2a7164ab6e70c2e23d567123206ca4caf 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -1297,6 +1297,35 @@ class V8_EXPORT StackFrame {
 };
 
 
+/* TODO(gholap): This should go away and struct Sample should
+                 just use const void* instead of Address.
+                 Currently we need it because of implementation details. */
+typedef unsigned char* Address;
+
+
+/**
+ * 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;
+
+  Address stack[kMaxFramesCount];  // Call stack.
+  unsigned frames_count;           // Number of captured frames.
+};
+
+
 /**
  * A JSON Parser.
  */
@@ -4217,6 +4246,11 @@ 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