WebApp: Use base::StrCat and StringPiece in GenerateApplicationNameFromURL

Modernize it.
Add unit test.

Bug: 860581
Change-Id: I136f85f234a843321b49976659f37aa2865ba318
Reviewed-on: https://chromium-review.googlesource.com/1139844
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575581}

chrome/browser/web_applications/BUILD.gn

@@ -60,5 +60,6 @@ source_set("unit_tests") {
   deps = [
     ":web_applications_unit_tests",
     "//chrome/browser/web_applications/bookmark_apps:unit_tests",
+    "//chrome/browser/web_applications/components:components_unit_tests",
   ]
 }

chrome/browser/web_applications/components/BUILD.gn

@@ -12,3 +12,17 @@ source_set("components") {
     "//base",
   ]
 }
+
+source_set("components_unit_tests") {
+  testonly = true
+
+  sources = [
+    "web_app_helpers_unittest.cc",
+  ]
+
+  deps = [
+    ":components",
+    "//testing/gtest",
+    "//url",
+  ]
+}

chrome/browser/web_applications/components/web_app_helpers.cc

@@ -4,16 +4,13 @@
 
 #include "chrome/browser/web_applications/components/web_app_helpers.h"
 
+#include "base/strings/strcat.h"
 #include "url/gurl.h"
 
 namespace web_app {
 
 std::string GenerateApplicationNameFromURL(const GURL& url) {
-  std::string t;
-  t.append(url.host());
-  t.append("_");
-  t.append(url.path());
-  return t;
+  return base::StrCat({url.host_piece(), "_", url.path_piece()});
 }
 
 }  // namespace web_app

chrome/browser/web_applications/components/web_app_helpers_unittest.cc

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/web_applications/components/web_app_helpers.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "url/gurl.h"
+
+namespace web_app {
+
+TEST(WebAppHelpers, GenerateApplicationNameFromURL) {
+  EXPECT_EQ("_", GenerateApplicationNameFromURL(GURL()));
+
+  EXPECT_EQ("example.com_/",
+            GenerateApplicationNameFromURL(GURL("http://example.com")));
+
+  EXPECT_EQ("example.com_/path",
+            GenerateApplicationNameFromURL(GURL("https://example.com/path")));
+}
+
+}  // namespace web_app