diff --git a/include/cef.h b/include/cef.h
index 4049a74b..97e69679 100644
--- a/include/cef.h
+++ b/include/cef.h
@@ -2663,8 +2663,8 @@ public:
   ///
   // Returns true if the object has a value with the specified identifier.
   ///
-  /*--cef(capi_name=has_value_byindex)--*/
-  virtual bool HasValue(size_t index) =0;
+  /*--cef(capi_name=has_value_byindex,index_param=index)--*/
+  virtual bool HasValue(int index) =0;
 
   ///
   // Delete the value with the specified identifier.
@@ -2674,8 +2674,8 @@ public:
   ///
   // Delete the value with the specified identifier.
   ///
-  /*--cef(capi_name=delete_value_byindex)--*/
-  virtual bool DeleteValue(size_t index) =0;
+  /*--cef(capi_name=delete_value_byindex,index_param=index)--*/
+  virtual bool DeleteValue(int index) =0;
 
   ///
   // Returns the value with the specified identifier.
@@ -2685,8 +2685,8 @@ public:
   ///
   // Returns the value with the specified identifier.
   ///
-  /*--cef(capi_name=get_value_byindex)--*/
-  virtual CefRefPtr<CefV8Value> GetValue(size_t index) =0;
+  /*--cef(capi_name=get_value_byindex,index_param=index)--*/
+  virtual CefRefPtr<CefV8Value> GetValue(int index) =0;
 
   ///
   // Associate a value with the specified identifier.
@@ -2697,8 +2697,8 @@ public:
   ///
   // Associate a value with the specified identifier.
   ///
-  /*--cef(capi_name=set_value_byindex)--*/
-  virtual bool SetValue(size_t index, CefRefPtr<CefV8Value> value) =0;
+  /*--cef(capi_name=set_value_byindex,index_param=index)--*/
+  virtual bool SetValue(int index, CefRefPtr<CefV8Value> value) =0;
 
   ///
   // Register an identifier whose access will be forwarded to the CefV8Accessor
@@ -3137,8 +3137,8 @@ public:
   ///
   // Returns the value of the attribute at the specified 0-based index.
   ///
-  /*--cef(capi_name=get_attribute_byindex)--*/
-  virtual CefString GetAttribute(size_t index) =0;
+  /*--cef(capi_name=get_attribute_byindex,index_param=index)--*/
+  virtual CefString GetAttribute(int index) =0;
 
   ///
   // Returns the value of the attribute with the specified qualified name.
@@ -3182,8 +3182,8 @@ public:
   // Moves the cursor to the attribute at the specified 0-based index. Returns
   // true if the cursor position was set successfully.
   ///
-  /*--cef(capi_name=move_to_attribute_byindex)--*/
-  virtual bool MoveToAttribute(size_t index) =0;
+  /*--cef(capi_name=move_to_attribute_byindex,index_param=index)--*/
+  virtual bool MoveToAttribute(int index) =0;
 
   ///
   // Moves the cursor to the attribute with the specified qualified name.
diff --git a/include/cef_capi.h b/include/cef_capi.h
index cca6673b..e0c47306 100644
--- a/include/cef_capi.h
+++ b/include/cef_capi.h
@@ -2375,8 +2375,7 @@ typedef struct _cef_v8value_t
   ///
   // Returns true (1) if the object has a value with the specified identifier.
   ///
-  int (CEF_CALLBACK *has_value_byindex)(struct _cef_v8value_t* self,
-      size_t index);
+  int (CEF_CALLBACK *has_value_byindex)(struct _cef_v8value_t* self, int index);
 
   ///
   // Delete the value with the specified identifier.
@@ -2388,7 +2387,7 @@ typedef struct _cef_v8value_t
   // Delete the value with the specified identifier.
   ///
   int (CEF_CALLBACK *delete_value_byindex)(struct _cef_v8value_t* self,
-      size_t index);
+      int index);
 
   ///
   // Returns the value with the specified identifier.
@@ -2400,7 +2399,7 @@ typedef struct _cef_v8value_t
   // Returns the value with the specified identifier.
   ///
   struct _cef_v8value_t* (CEF_CALLBACK *get_value_byindex)(
-      struct _cef_v8value_t* self, size_t index);
+      struct _cef_v8value_t* self, int index);
 
   ///
   // Associate a value with the specified identifier.
@@ -2412,8 +2411,8 @@ typedef struct _cef_v8value_t
   ///
   // Associate a value with the specified identifier.
   ///
-  int (CEF_CALLBACK *set_value_byindex)(struct _cef_v8value_t* self,
-      size_t index, struct _cef_v8value_t* value);
+  int (CEF_CALLBACK *set_value_byindex)(struct _cef_v8value_t* self, int index,
+      struct _cef_v8value_t* value);
 
   ///
   // Register an identifier whose access will be forwarded to the
@@ -2917,7 +2916,7 @@ typedef struct _cef_xml_reader_t
   ///
   // The resulting string must be freed by calling cef_string_userfree_free().
   cef_string_userfree_t (CEF_CALLBACK *get_attribute_byindex)(
-      struct _cef_xml_reader_t* self, size_t index);
+      struct _cef_xml_reader_t* self, int index);
 
   ///
   // Returns the value of the attribute with the specified qualified name.
@@ -2965,7 +2964,7 @@ typedef struct _cef_xml_reader_t
   // true (1) if the cursor position was set successfully.
   ///
   int (CEF_CALLBACK *move_to_attribute_byindex)(struct _cef_xml_reader_t* self,
-      size_t index);
+      int index);
 
   ///
   // Moves the cursor to the attribute with the specified qualified name.
diff --git a/libcef/v8_impl.cc b/libcef/v8_impl.cc
index 10bfebcb..6d97094d 100644
--- a/libcef/v8_impl.cc
+++ b/libcef/v8_impl.cc
@@ -851,13 +851,17 @@ bool CefV8ValueImpl::HasValue(const CefString& key)
   return obj->Has(GetV8String(key));
 }
 
-bool CefV8ValueImpl::HasValue(size_t index)
+bool CefV8ValueImpl::HasValue(int index)
 {
   CEF_REQUIRE_UI_THREAD(false);
   if(!GetHandle()->IsObject()) {
     NOTREACHED() << "V8 value is not an object";
     return false;
   }
+  if (index < 0) {
+    NOTREACHED() << "invalid input parameter";
+    return false;
+  }
 
   v8::HandleScope handle_scope;
   v8::Local<v8::Object> obj = GetHandle()->ToObject();
@@ -882,13 +886,17 @@ bool CefV8ValueImpl::DeleteValue(const CefString& key)
   return obj->Delete(GetV8String(key));
 }
 
-bool CefV8ValueImpl::DeleteValue(size_t index)
+bool CefV8ValueImpl::DeleteValue(int index)
 {
   CEF_REQUIRE_UI_THREAD(false);
   if(!GetHandle()->IsObject()) {
     NOTREACHED() << "V8 value is not an object";
     return false;
   }
+  if (index < 0) {
+    NOTREACHED() << "invalid input parameter";
+    return false;
+  }
 
   v8::HandleScope handle_scope;
   v8::Local<v8::Object> obj = GetHandle()->ToObject();
@@ -913,13 +921,17 @@ CefRefPtr<CefV8Value> CefV8ValueImpl::GetValue(const CefString& key)
   return new CefV8ValueImpl(obj->Get(GetV8String(key)));
 }
 
-CefRefPtr<CefV8Value> CefV8ValueImpl::GetValue(size_t index)
+CefRefPtr<CefV8Value> CefV8ValueImpl::GetValue(int index)
 {
   CEF_REQUIRE_UI_THREAD(NULL);
   if(!GetHandle()->IsObject()) {
     NOTREACHED() << "V8 value is not an object";
     return NULL;
   }
+  if (index < 0) {
+    NOTREACHED() << "invalid input parameter";
+    return false;
+  }
 
   v8::HandleScope handle_scope;
   v8::Local<v8::Object> obj = GetHandle()->ToObject();
@@ -948,7 +960,7 @@ bool CefV8ValueImpl::SetValue(const CefString& key,
   }
 }
 
-bool CefV8ValueImpl::SetValue(size_t index, CefRefPtr<CefV8Value> value)
+bool CefV8ValueImpl::SetValue(int index, CefRefPtr<CefV8Value> value)
 {
   CEF_REQUIRE_UI_THREAD(false);
 
@@ -956,6 +968,10 @@ bool CefV8ValueImpl::SetValue(size_t index, CefRefPtr<CefV8Value> value)
     NOTREACHED() << "V8 value is not an object";
     return false;
   }
+  if (index < 0) {
+    NOTREACHED() << "invalid input parameter";
+    return false;
+  }
 
   CefV8ValueImpl *impl = static_cast<CefV8ValueImpl*>(value.get());
   if(impl) {
diff --git a/libcef/v8_impl.h b/libcef/v8_impl.h
index 2d56f2b6..4eec2275 100644
--- a/libcef/v8_impl.h
+++ b/libcef/v8_impl.h
@@ -127,14 +127,14 @@ public:
   virtual CefTime GetDateValue() OVERRIDE;
   virtual CefString GetStringValue() OVERRIDE;
   virtual bool HasValue(const CefString& key) OVERRIDE;
-  virtual bool HasValue(size_t index) OVERRIDE;
+  virtual bool HasValue(int index) OVERRIDE;
   virtual bool DeleteValue(const CefString& key) OVERRIDE;
-  virtual bool DeleteValue(size_t index) OVERRIDE;
+  virtual bool DeleteValue(int index) OVERRIDE;
   virtual CefRefPtr<CefV8Value> GetValue(const CefString& key) OVERRIDE;
-  virtual CefRefPtr<CefV8Value> GetValue(size_t index) OVERRIDE;
+  virtual CefRefPtr<CefV8Value> GetValue(int index) OVERRIDE;
   virtual bool SetValue(const CefString& key, CefRefPtr<CefV8Value> value,
                         PropertyAttribute attribute) OVERRIDE;
-  virtual bool SetValue(size_t index, CefRefPtr<CefV8Value> value) OVERRIDE;
+  virtual bool SetValue(int index, CefRefPtr<CefV8Value> value) OVERRIDE;
   virtual bool SetValue(const CefString& key, AccessControl settings, 
                         PropertyAttribute attribute) OVERRIDE;
   virtual bool GetKeys(std::vector<CefString>& keys) OVERRIDE;
diff --git a/libcef/xml_reader_impl.cc b/libcef/xml_reader_impl.cc
index 2921e581..0215b58d 100644
--- a/libcef/xml_reader_impl.cc
+++ b/libcef/xml_reader_impl.cc
@@ -355,7 +355,7 @@ size_t CefXmlReaderImpl::GetAttributeCount()
   return xmlTextReaderAttributeCount(reader_);
 }
 
-CefString CefXmlReaderImpl::GetAttribute(size_t index)
+CefString CefXmlReaderImpl::GetAttribute(int index)
 {
   if (!VerifyContext())
     return CefString();
@@ -409,7 +409,7 @@ int CefXmlReaderImpl::GetLineNumber()
   return xmlTextReaderGetParserLineNumber(reader_);
 }
 
-bool CefXmlReaderImpl::MoveToAttribute(size_t index)
+bool CefXmlReaderImpl::MoveToAttribute(int index)
 {
   if (!VerifyContext())
     return false;
diff --git a/libcef/xml_reader_impl.h b/libcef/xml_reader_impl.h
index 9d8ceb46..1de73375 100644
--- a/libcef/xml_reader_impl.h
+++ b/libcef/xml_reader_impl.h
@@ -38,14 +38,14 @@ public:
   virtual CefString GetValue() OVERRIDE;
   virtual bool HasAttributes() OVERRIDE;
   virtual size_t GetAttributeCount() OVERRIDE;
-  virtual CefString GetAttribute(size_t index) OVERRIDE;
+  virtual CefString GetAttribute(int index) OVERRIDE;
   virtual CefString GetAttribute(const CefString& qualifiedName) OVERRIDE;
   virtual CefString GetAttribute(const CefString& localName,
                                  const CefString& namespaceURI) OVERRIDE;
   virtual CefString GetInnerXml() OVERRIDE;
   virtual CefString GetOuterXml() OVERRIDE;
   virtual int GetLineNumber() OVERRIDE;
-  virtual bool MoveToAttribute(size_t index) OVERRIDE;
+  virtual bool MoveToAttribute(int index) OVERRIDE;
   virtual bool MoveToAttribute(const CefString& qualifiedName) OVERRIDE;
   virtual bool MoveToAttribute(const CefString& localName,
                                const CefString& namespaceURI) OVERRIDE;
diff --git a/libcef_dll/cpptoc/v8value_cpptoc.cc b/libcef_dll/cpptoc/v8value_cpptoc.cc
index 25513f51..057ca58e 100644
--- a/libcef_dll/cpptoc/v8value_cpptoc.cc
+++ b/libcef_dll/cpptoc/v8value_cpptoc.cc
@@ -477,13 +477,17 @@ int CEF_CALLBACK v8value_has_value_bykey(struct _cef_v8value_t* self,
 
 
 int CEF_CALLBACK v8value_has_value_byindex(struct _cef_v8value_t* self,
-    size_t index)
+    int index)
 {
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
   DCHECK(self);
   if (!self)
     return 0;
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return 0;
 
   // Execute
   bool _retval = CefV8ValueCppToC::Get(self)->HasValue(
@@ -517,13 +521,17 @@ int CEF_CALLBACK v8value_delete_value_bykey(struct _cef_v8value_t* self,
 
 
 int CEF_CALLBACK v8value_delete_value_byindex(struct _cef_v8value_t* self,
-    size_t index)
+    int index)
 {
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
   DCHECK(self);
   if (!self)
     return 0;
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return 0;
 
   // Execute
   bool _retval = CefV8ValueCppToC::Get(self)->DeleteValue(
@@ -557,13 +565,17 @@ struct _cef_v8value_t* CEF_CALLBACK v8value_get_value_bykey(
 
 
 struct _cef_v8value_t* CEF_CALLBACK v8value_get_value_byindex(
-    struct _cef_v8value_t* self, size_t index)
+    struct _cef_v8value_t* self, int index)
 {
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
   DCHECK(self);
   if (!self)
     return NULL;
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return NULL;
 
   // Execute
   CefRefPtr<CefV8Value> _retval = CefV8ValueCppToC::Get(self)->GetValue(
@@ -604,13 +616,17 @@ int CEF_CALLBACK v8value_set_value_bykey(struct _cef_v8value_t* self,
 
 
 int CEF_CALLBACK v8value_set_value_byindex(struct _cef_v8value_t* self,
-    size_t index, struct _cef_v8value_t* value)
+    int index, struct _cef_v8value_t* value)
 {
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
   DCHECK(self);
   if (!self)
     return 0;
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return 0;
   // Verify param: value; type: refptr_same
   DCHECK(value);
   if (!value)
diff --git a/libcef_dll/cpptoc/xml_reader_cpptoc.cc b/libcef_dll/cpptoc/xml_reader_cpptoc.cc
index 14aee2ee..e79344d3 100644
--- a/libcef_dll/cpptoc/xml_reader_cpptoc.cc
+++ b/libcef_dll/cpptoc/xml_reader_cpptoc.cc
@@ -327,13 +327,17 @@ size_t CEF_CALLBACK xml_reader_get_attribute_count(
 
 
 cef_string_userfree_t CEF_CALLBACK xml_reader_get_attribute_byindex(
-    struct _cef_xml_reader_t* self, size_t index)
+    struct _cef_xml_reader_t* self, int index)
 {
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
   DCHECK(self);
   if (!self)
     return NULL;
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return NULL;
 
   // Execute
   CefString _retval = CefXmlReaderCppToC::Get(self)->GetAttribute(
@@ -445,13 +449,17 @@ int CEF_CALLBACK xml_reader_get_line_number(struct _cef_xml_reader_t* self)
 
 
 int CEF_CALLBACK xml_reader_move_to_attribute_byindex(
-    struct _cef_xml_reader_t* self, size_t index)
+    struct _cef_xml_reader_t* self, int index)
 {
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
   DCHECK(self);
   if (!self)
     return 0;
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return 0;
 
   // Execute
   bool _retval = CefXmlReaderCppToC::Get(self)->MoveToAttribute(
diff --git a/libcef_dll/ctocpp/v8value_ctocpp.cc b/libcef_dll/ctocpp/v8value_ctocpp.cc
index adf9739d..78adb9d9 100644
--- a/libcef_dll/ctocpp/v8value_ctocpp.cc
+++ b/libcef_dll/ctocpp/v8value_ctocpp.cc
@@ -452,13 +452,18 @@ bool CefV8ValueCToCpp::HasValue(const CefString& key)
 }
 
 
-bool CefV8ValueCToCpp::HasValue(size_t index)
+bool CefV8ValueCToCpp::HasValue(int index)
 {
   if (CEF_MEMBER_MISSING(struct_, has_value_byindex))
     return false;
 
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return false;
+
   // Execute
   int _retval = struct_->has_value_byindex(struct_,
       index);
@@ -489,13 +494,18 @@ bool CefV8ValueCToCpp::DeleteValue(const CefString& key)
 }
 
 
-bool CefV8ValueCToCpp::DeleteValue(size_t index)
+bool CefV8ValueCToCpp::DeleteValue(int index)
 {
   if (CEF_MEMBER_MISSING(struct_, delete_value_byindex))
     return false;
 
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return false;
+
   // Execute
   int _retval = struct_->delete_value_byindex(struct_,
       index);
@@ -526,13 +536,18 @@ CefRefPtr<CefV8Value> CefV8ValueCToCpp::GetValue(const CefString& key)
 }
 
 
-CefRefPtr<CefV8Value> CefV8ValueCToCpp::GetValue(size_t index)
+CefRefPtr<CefV8Value> CefV8ValueCToCpp::GetValue(int index)
 {
   if (CEF_MEMBER_MISSING(struct_, get_value_byindex))
     return NULL;
 
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return NULL;
+
   // Execute
   cef_v8value_t* _retval = struct_->get_value_byindex(struct_,
       index);
@@ -570,13 +585,17 @@ bool CefV8ValueCToCpp::SetValue(const CefString& key,
 }
 
 
-bool CefV8ValueCToCpp::SetValue(size_t index, CefRefPtr<CefV8Value> value)
+bool CefV8ValueCToCpp::SetValue(int index, CefRefPtr<CefV8Value> value)
 {
   if (CEF_MEMBER_MISSING(struct_, set_value_byindex))
     return false;
 
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return false;
   // Verify param: value; type: refptr_same
   DCHECK(value.get());
   if (!value.get())
diff --git a/libcef_dll/ctocpp/v8value_ctocpp.h b/libcef_dll/ctocpp/v8value_ctocpp.h
index d570075e..c824d03d 100644
--- a/libcef_dll/ctocpp/v8value_ctocpp.h
+++ b/libcef_dll/ctocpp/v8value_ctocpp.h
@@ -49,14 +49,14 @@ public:
   virtual CefTime GetDateValue() OVERRIDE;
   virtual CefString GetStringValue() OVERRIDE;
   virtual bool HasValue(const CefString& key) OVERRIDE;
-  virtual bool HasValue(size_t index) OVERRIDE;
+  virtual bool HasValue(int index) OVERRIDE;
   virtual bool DeleteValue(const CefString& key) OVERRIDE;
-  virtual bool DeleteValue(size_t index) OVERRIDE;
+  virtual bool DeleteValue(int index) OVERRIDE;
   virtual CefRefPtr<CefV8Value> GetValue(const CefString& key) OVERRIDE;
-  virtual CefRefPtr<CefV8Value> GetValue(size_t index) OVERRIDE;
+  virtual CefRefPtr<CefV8Value> GetValue(int index) OVERRIDE;
   virtual bool SetValue(const CefString& key, CefRefPtr<CefV8Value> value,
       PropertyAttribute attribute) OVERRIDE;
-  virtual bool SetValue(size_t index, CefRefPtr<CefV8Value> value) OVERRIDE;
+  virtual bool SetValue(int index, CefRefPtr<CefV8Value> value) OVERRIDE;
   virtual bool SetValue(const CefString& key, AccessControl settings,
       PropertyAttribute attribute) OVERRIDE;
   virtual bool GetKeys(std::vector<CefString>& keys) OVERRIDE;
diff --git a/libcef_dll/ctocpp/xml_reader_ctocpp.cc b/libcef_dll/ctocpp/xml_reader_ctocpp.cc
index 75899225..23f7351b 100644
--- a/libcef_dll/ctocpp/xml_reader_ctocpp.cc
+++ b/libcef_dll/ctocpp/xml_reader_ctocpp.cc
@@ -315,13 +315,18 @@ size_t CefXmlReaderCToCpp::GetAttributeCount()
 }
 
 
-CefString CefXmlReaderCToCpp::GetAttribute(size_t index)
+CefString CefXmlReaderCToCpp::GetAttribute(int index)
 {
   if (CEF_MEMBER_MISSING(struct_, get_attribute_byindex))
     return CefString();
 
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return CefString();
+
   // Execute
   cef_string_userfree_t _retval = struct_->get_attribute_byindex(struct_,
       index);
@@ -434,13 +439,18 @@ int CefXmlReaderCToCpp::GetLineNumber()
 }
 
 
-bool CefXmlReaderCToCpp::MoveToAttribute(size_t index)
+bool CefXmlReaderCToCpp::MoveToAttribute(int index)
 {
   if (CEF_MEMBER_MISSING(struct_, move_to_attribute_byindex))
     return false;
 
   // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
 
+  // Verify param: index; type: simple_byval
+  DCHECK(index >= 0);
+  if (index < 0)
+    return false;
+
   // Execute
   int _retval = struct_->move_to_attribute_byindex(struct_,
       index);
diff --git a/libcef_dll/ctocpp/xml_reader_ctocpp.h b/libcef_dll/ctocpp/xml_reader_ctocpp.h
index acf8745f..27bbdc70 100644
--- a/libcef_dll/ctocpp/xml_reader_ctocpp.h
+++ b/libcef_dll/ctocpp/xml_reader_ctocpp.h
@@ -49,14 +49,14 @@ public:
   virtual CefString GetValue() OVERRIDE;
   virtual bool HasAttributes() OVERRIDE;
   virtual size_t GetAttributeCount() OVERRIDE;
-  virtual CefString GetAttribute(size_t index) OVERRIDE;
+  virtual CefString GetAttribute(int index) OVERRIDE;
   virtual CefString GetAttribute(const CefString& qualifiedName) OVERRIDE;
   virtual CefString GetAttribute(const CefString& localName,
       const CefString& namespaceURI) OVERRIDE;
   virtual CefString GetInnerXml() OVERRIDE;
   virtual CefString GetOuterXml() OVERRIDE;
   virtual int GetLineNumber() OVERRIDE;
-  virtual bool MoveToAttribute(size_t index) OVERRIDE;
+  virtual bool MoveToAttribute(int index) OVERRIDE;
   virtual bool MoveToAttribute(const CefString& qualifiedName) OVERRIDE;
   virtual bool MoveToAttribute(const CefString& localName,
       const CefString& namespaceURI) OVERRIDE;
diff --git a/tools/make_cpptoc_impl.py b/tools/make_cpptoc_impl.py
index e3d366d7..e1c8293c 100644
--- a/tools/make_cpptoc_impl.py
+++ b/tools/make_cpptoc_impl.py
@@ -114,6 +114,14 @@ def make_cpptoc_function_impl_new(name, func, defined_names):
                       '\n  if ('+arg_name+'Count > 0 && !'+arg_name+')'\
                       '\n    return'+retval_default+';'
 
+        # check index params
+        index_params = arg.parent.get_attrib_list('index_param')
+        if not index_params is None and arg_name in index_params:
+            result += comment+\
+                      '\n  DCHECK('+arg_name+' >= 0);'\
+                      '\n  if ('+arg_name+' < 0)'\
+                      '\n    return'+retval_default+';'
+
     if len(optional) > 0:
         result += '\n  // Unverified params: '+string.join(optional,', ')
     
diff --git a/tools/make_ctocpp_impl.py b/tools/make_ctocpp_impl.py
index a74cb56e..dd8a7496 100644
--- a/tools/make_ctocpp_impl.py
+++ b/tools/make_ctocpp_impl.py
@@ -118,7 +118,15 @@ def make_ctocpp_function_impl_new(clsname, name, func):
             result += comment+\
                       '\n  DCHECK(!'+arg_name+'.empty());'\
                       '\n  if ('+arg_name+'.empty())'\
-                      '\n    return'+retval_default+';'            
+                      '\n    return'+retval_default+';'  
+
+        # check index params
+        index_params = arg.parent.get_attrib_list('index_param')
+        if not index_params is None and arg_name in index_params:
+            result += comment+\
+                      '\n  DCHECK('+arg_name+' >= 0);'\
+                      '\n  if ('+arg_name+' < 0)'\
+                      '\n    return'+retval_default+';'
 
     if len(optional) > 0:
         result += '\n  // Unverified params: '+string.join(optional,', ')
diff --git a/tools/translator.README.txt b/tools/translator.README.txt
index b4f0fe16..1c5b8645 100644
--- a/tools/translator.README.txt
+++ b/tools/translator.README.txt
@@ -79,6 +79,8 @@ Supported method/function attributes:
                            resulting C API function.
    optional_param=[param]  (Optional) Parameter name that will be optional
                            instead of required.
+   index_param=[param]     (Optional) Parameter name representing an index
+                           value that will be verified as >= 0.
    default_retval=[string] (Required for enumeration types, Optional for other
                            types) Specify the default return value.
    count_func=[param:func] (Required for non-const non-string std::vector