Use StringView for String::append and ::insert.

third_party/WebKit/Source/platform/graphics/LoggingCanvas.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 283 matching lines @@
 {
     std::unique_ptr<JSONObject> shaderItem = JSONObject::create();
     const SkMatrix localMatrix = shader.getLocalMatrix();
     if (!localMatrix.isIdentity())
         shaderItem->setArray("localMatrix", arrayForSkMatrix(localMatrix));
     return shaderItem;
 }
 
 String stringForSkColor(const SkColor& color)
 {
-    String colorString = "#";
-    appendUnsignedAsHex(color, colorString);
-    return colorString;
+    // #AARRGGBB.
+    Vector<LChar, 9> result;
+    result.append('#');
+    appendUnsignedAsHex(color, result);
+    return String(result.data(), result.size());
 }
 
 void appendFlagToString(String* flagsString, bool isSet, const String& name)
 {
     if (!isSet)
         return;
     if (flagsString->length())
         flagsString->append("|");
     flagsString->append(name);
 }
@@ skipping 541 matching lines @@
     return pictureAsJSON->toPrettyJSONString();
 }
 
 void showSkPicture(const SkPicture* picture)
 {
     WTFLogAlways("%s\n", pictureAsDebugString(picture).utf8().data());
 }
 #endif
 
 } // namespace blink