[inspector] Fix and refactor String16

src/inspector/v8-debugger-agent-impl.cc

Index: src/inspector/v8-debugger-agent-impl.cc
diff --git a/src/inspector/v8-debugger-agent-impl.cc b/src/inspector/v8-debugger-agent-impl.cc
index ab4e349909865e93c5c2ecc23f888dd16a45e6da..ae7cad284588e9a822112d8a310963f870e301e5 100644
--- a/src/inspector/v8-debugger-agent-impl.cc
+++ b/src/inspector/v8-debugger-agent-impl.cc
@@ -76,8 +76,8 @@ static String16 breakpointIdSuffix(
 static String16 generateBreakpointId(
     const String16& scriptId, int lineNumber, int columnNumber,
     V8DebuggerAgentImpl::BreakpointSource source) {
-  return scriptId + ":" + String16::fromInteger(lineNumber) + ":" +
-         String16::fromInteger(columnNumber) + breakpointIdSuffix(source);
+  return String16::concat(scriptId, ':', lineNumber, ':', columnNumber,
+                          breakpointIdSuffix(source));
 }
 
 static bool positionComparator(const std::pair<int, int>& a,