dpwa: Reintroduce GenerateIconLetterFromUrl fallback to generate icons.

We still need it: the title can be empty in some scenarios.

Looks like we need to generate some icon based on url
to show this icon for a user in web app install dialog, where
user should enter a non-empty title.

1) WebAppInstallTask::OnIconsRetrievedShowDialog()
2) FilterAndResizeIconsGenerateMissing()
3) Show dialog with the generated icon, `title` is still empty here.

This is a partial revert of
https://chromium-review.googlesource.com/c/chromium/src/+/2312056

The title populating code is left there in unit tests.

Bug: 1109540, 1103570
Change-Id: Ia281397d3483ad08d02ae4a9f0e2ca60bd34e859
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2319493Reviewed-by: Alan Cutter <alancutter@chromium.org>
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791776}

chrome/browser/web_applications/components/web_app_icon_generator.cc

@@ -177,6 +177,27 @@ SkBitmap GenerateBitmap(SquareSizePx output_size,
   return dst;
 }
 
+base::char16 GenerateIconLetterFromUrl(const GURL& app_url) {
+  std::string app_url_part = " ";
+  const std::string domain_and_registry =
+      net::registry_controlled_domains::GetDomainAndRegistry(
+          app_url,
+          net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES);
+
+  if (!domain_and_registry.empty()) {
+    app_url_part = domain_and_registry;
+  } else if (app_url.has_host()) {
+    app_url_part = app_url.host();
+  }
+
+  // Translate punycode into unicode before retrieving the first letter.
+  const base::string16 string_for_display =
+      url_formatter::IDNToUnicode(app_url_part);
+
+  base::char16 icon_letter = base::i18n::ToUpper(string_for_display)[0];
+  return icon_letter;
+}
+
 base::char16 GenerateIconLetterFromAppName(const base::string16& app_name) {
   CHECK(!app_name.empty());
   return base::i18n::ToUpper(app_name)[0];

chrome/browser/web_applications/components/web_app_icon_generator.h

@@ -55,6 +55,10 @@ SkBitmap GenerateBitmap(SquareSizePx output_size,
                         SkColor color,
                         base::char16 icon_letter);
 
+// Returns the first letter from |app_url| that will be painted on the generated
+// icon.
+base::char16 GenerateIconLetterFromUrl(const GURL& app_url);
+
 // Returns the first letter from |app_name| that will be painted on the
 // generated icon.
 base::char16 GenerateIconLetterFromAppName(const base::string16& app_name);

chrome/browser/web_applications/components/web_app_icon_generator_unittest.cc

@@ -354,6 +354,17 @@ TEST_F(WebAppIconGeneratorTest, IconsResizedWhenOnlyAGigantorOneIsProvided) {
   TestIconGeneration(icon_size::k512, 0, 3);
 }
 
+TEST_F(WebAppIconGeneratorTest, GenerateIconLetterFromUrl) {
+  // ASCII:
+  EXPECT_EQ('E', GenerateIconLetterFromUrl(GURL("http://example.com")));
+  // Cyrillic capital letter ZHE for something like https://zhuk.rf:
+  EXPECT_EQ(0x0416,
+            GenerateIconLetterFromUrl(GURL("https://xn--f1ai0a.xn--p1ai/")));
+  // Arabic:
+  EXPECT_EQ(0x0645,
+            GenerateIconLetterFromUrl(GURL("http://xn--mgbh0fb.example/")));
+}
+
 TEST_F(WebAppIconGeneratorTest, GenerateIconLetterFromAppName) {
   // ASCII Encoding
   EXPECT_EQ('T',

chrome/browser/web_applications/components/web_app_install_utils.cc

@@ -282,9 +282,10 @@ void FilterAndResizeIconsGenerateMissing(WebApplicationInfo* web_app_info,
   }
   FilterSquareIconsFromBitmaps(web_app_info->icon_bitmaps_any, &square_icons);
 
-  DCHECK(!web_app_info->title.empty());
-  base::char16 icon_letter = GenerateIconLetterFromAppName(web_app_info->title);
-
+  base::char16 icon_letter =
+      web_app_info->title.empty()
+          ? GenerateIconLetterFromUrl(web_app_info->app_url)
+          : GenerateIconLetterFromAppName(web_app_info->title);
   web_app_info->generated_icon_color = SK_ColorTRANSPARENT;
   // TODO(https://crbug.com/1029223): Don't resize before writing to disk, it's
   // not necessary and would simplify this code path to remove.