Add API for get the memory stats (#1923)

JerryScript-DCO-1.0-Signed-off-by: Zidong Jiang zidong.jiang@intel.com

docs/02.API-REFERENCE.md

@@ -169,6 +169,26 @@ typedef struct
 } jerry_property_descriptor_t;
 ```
 
+## jerry_heap_stats_t
+
+**summary**
+
+Description of JerryScript heap memory stats.
+It is for memory profiling.
+
+**Prototype**
+
+```c
+typedef struct
+{
+  size_t version /**< the version of the stats struct */
+  size_t size; /**< heap total size */
+  size_t allocated_bytes; /**< currently allocated bytes */
+  size_t peak_allocated_bytes; /**< peak allocated bytes */
+  size_t reserved[4]; /**< padding for future extensions */
+} jerry_heap_stats_t;
+```
+
 ## jerry_external_handler_t
 
 **Summary**
@@ -523,6 +543,36 @@ main (void)
 - [jerry_cleanup](#jerry_cleanup)
 
 
+## jerry_get_memory_stats
+
+**Summary**
+
+Get heap memory stats.
+
+**Prototype**
+
+```c
+bool
+jerry_get_memory_stats (jerry_heap_stats_t *out_stats_p);
+```
+
+- `out_stats_p` - out parameter, that provides the heap statistics.
+- return value
+  - true, if run was successful
+  - false, otherwise. Usually it is because the MEM_STATS feature is not enabled.
+
+**Example**
+
+```c
+jerry_heap_stats_t stats = {0};
+bool get_stats_ret = jerry_get_memory_stats (&stats);
+```
+
+**See also**
+
+- [jerry_init](#jerry_init)
+
+
 ## jerry_gc
 
 **Summary**