Fix DCHECK() failure when invoking Translate on about:blank page.

"about:blank" should not be a translatable URL.

Bug: 960369
Change-Id: Ife979fd641a793d8e4442309c436c6c0dd07c876
Fixed: 960369
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1946870Reviewed-by: John Wu <jzw@chromium.org>
Commit-Queue: Fei Ling <feiling@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721188}

chrome/browser/translate/translate_service.cc

@@ -133,11 +133,12 @@ bool TranslateService::IsTranslatableURL(const GURL& url) {
   // - empty (can happen for popups created with window.open(""))
   // - an internal URL (chrome:// and others)
   // - the devtools (which is considered UI)
+  // - about:blank
   // - Chrome OS file manager extension
   // - an FTP page (as FTP pages tend to have long lists of filenames that may
   //   confuse the CLD)
   return !url.is_empty() && !url.SchemeIs(content::kChromeUIScheme) &&
-         !url.SchemeIs(content::kChromeDevToolsScheme) &&
+         !url.SchemeIs(content::kChromeDevToolsScheme) && !url.IsAboutBlank() &&
 #if defined(OS_CHROMEOS)
          !(url.SchemeIs(extensions::kExtensionScheme) &&
            url.DomainIs(file_manager::kFileManagerAppId)) &&

chrome/browser/translate/translate_service_unittest.cc

@@ -24,6 +24,9 @@ TEST(TranslateServiceTest, CheckTranslatableURL) {
   GURL empty_url = GURL(std::string());
   EXPECT_FALSE(TranslateService::IsTranslatableURL(empty_url));
 
+  GURL about_blank_url = GURL("about:blank");
+  EXPECT_FALSE(TranslateService::IsTranslatableURL(about_blank_url));
+
   std::string chrome = std::string(content::kChromeUIScheme) + "://flags";
   GURL chrome_url = GURL(chrome);
   EXPECT_FALSE(TranslateService::IsTranslatableURL(chrome_url));