Fix chrome://x-callback-url support.

kExternalFilesLoadedInWebState flag forced to load all external URL in
WebState which broke the support for chrome://x-callback-url URLs.

This CL enables kExternalFilesLoadedInWebState codepath only for file://
URLs, because WebState can only load file URLs. With this change
ExternalFileController is still not used when
kExternalFilesLoadedInWebState is enabled.

Bug: 923869
Change-Id: Iff438df5f8abb14dc85338acf18a3403fe3acd68
Reviewed-on: https://chromium-review.googlesource.com/c/1432593
Commit-Queue: Peter Lee <pkl@chromium.org>
Auto-Submit: Eugene But <eugenebut@chromium.org>
Reviewed-by: Peter Lee <pkl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625830}

ios/chrome/app/application_delegate/user_activity_handler.mm

@@ -265,18 +265,18 @@ NSString* const kShortcutQRScanner = @"OpenQRScanner";
             : ApplicationMode::NORMAL;
     GURL URL;
     GURL virtualURL;
-    if (base::FeatureList::IsEnabled(
+    GURL completeURL = startupInformation.startupParameters.completeURL;
+    GURL externalURL = startupInformation.startupParameters.externalURL;
+    if (completeURL.SchemeIsFile() &&
+        base::FeatureList::IsEnabled(
             experimental_flags::kExternalFilesLoadedInWebState)) {
       // External URL will be loaded by WebState, which expects |completeURL|.
       // Omnibox however suppose to display |externalURL|, which is used as
       // virtual URL.
-      URL = startupInformation.startupParameters.completeURL;
-      virtualURL = startupInformation.startupParameters.externalURL;
+      URL = completeURL;
+      virtualURL = externalURL;
     } else {
-      // |externalURL| is rewritten to chrome:// URL, which is expected by
-      // ExternalFileController. ExternalFileController will be used to load
-      // file:// URL. TODO(crbug.com/913602): Remove this code.
-      URL = startupInformation.startupParameters.externalURL;
+      URL = externalURL;
     }
     [tabOpener dismissModalsAndOpenSelectedTabInMode:targetMode
                                              withURL:URL

ios/chrome/app/application_delegate/user_activity_handler_unittest.mm

@@ -575,11 +575,7 @@ TEST_P(UserActivityHandlerTest, HandleStartupParamsNonU2F) {
   // Tests.
   EXPECT_OCMOCK_VERIFY(startupInformationMock);
   EXPECT_EQ(gurl, tabOpener.url);
-  if (GetParam() == ExternalFilesLoadedInWebStateFeature::Enabled) {
-    EXPECT_EQ(gurl, tabOpener.virtualURL);
-  } else {
-    EXPECT_TRUE(tabOpener.virtualURL.is_empty());
-  }
+  EXPECT_TRUE(tabOpener.virtualURL.is_empty());
   EXPECT_EQ(ApplicationMode::INCOGNITO, [tabOpener applicationMode]);
 }