Don't double-prompt for uses of facetime:// and tel:// URLs.

On iOS 10.3.2 (beta), the system is issuing confirmation prompts when
facetime:// or facetime-audio:// URLs are opened. This makes the
prompt generated by Chrome redundant and annoying to users of 10.3.2.

This CL checks for iOS version and prompts only when necessary.
Also removed the use of telprompt:// which may not be acceptable under
some interpretations.

BUG=710446
TEST=Please verify on the major supported versions of iOS, i.e. 9.x, 10.3, and the new 10.3.2 beta.

Review-Url: https://codereview.chromium.org/2815403003
Cr-Commit-Position: refs/heads/master@{#464639}

ios/chrome/browser/web/external_app_launcher.mm

@@ -4,6 +4,7 @@
 
 #import "ios/chrome/browser/web/external_app_launcher.h"
 
+#include "base/ios/ios_util.h"
 #include "base/ios/weak_nsobject.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
@@ -47,13 +48,30 @@ void RecordExternalApplicationOpened(bool opened) {
   UMA_HISTOGRAM_BOOLEAN("Tab.ExternalApplicationOpened", opened);
 }
 
+// Returns whether gURL has the scheme of a URL that initiates a call.
+BOOL UrlHasPhoneCallScheme(const GURL& gURL) {
+  return gURL.SchemeIs("tel") || gURL.SchemeIs("facetime") ||
+         gURL.SchemeIs("facetime-audio");
+}
+
+// Returns a string to be used as the label for the prompt's action button.
+NSString* PromptActionString(NSString* scheme) {
+  if ([scheme isEqualToString:@"facetime"])
+    return l10n_util::GetNSString(IDS_IOS_FACETIME_BUTTON);
+  else if ([scheme isEqualToString:@"tel"] ||
+           [scheme isEqualToString:@"facetime-audio"])
+    return l10n_util::GetNSString(IDS_IOS_PHONE_CALL_BUTTON);
+  NOTREACHED();
+  return @"";
+}
+
 }  // namespace
 
 @interface ExternalAppLauncher ()
 // Returns the Phone/FaceTime call argument from |URL|.
 + (NSString*)formatCallArgument:(NSURL*)URL;
-// Ask user for confirmation before dialing FaceTime destination.
-- (void)openFaceTimePromptForURL:(NSURL*)telURL;
+// Ask user for confirmation before dialing Phone or FaceTime destinations.
+- (void)openPromptForURL:(NSURL*)URL;
 // Ask user for confirmation before moving to external app.
 - (void)openExternalAppWithPromptForURL:(NSURL*)URL;
 // Presents a configured alert controller on the root view controller.
@@ -96,10 +114,9 @@ - (void)openExternalAppWithPromptForURL:(NSURL*)URL {
       }];
 }
 
-- (void)openFaceTimePromptForURL:(NSURL*)URL {
-  NSString* openTitle = l10n_util::GetNSString(IDS_IOS_FACETIME_BUTTON);
+- (void)openPromptForURL:(NSURL*)URL {
   [self presentAlertControllerWithMessage:[[self class] formatCallArgument:URL]
-                                openTitle:openTitle
+                                openTitle:PromptActionString(URL.scheme)
                               openHandler:^(UIAlertAction* action) {
                                 OpenUrlWithCompletionHandler(URL, nil);
                               }
@@ -136,26 +153,20 @@ - (BOOL)openURL:(const GURL&)gURL linkClicked:(BOOL)linkClicked {
     return NO;
   NSURL* URL = net::NSURLWithGURL(gURL);
 
-  if (gURL.SchemeIs("facetime") || gURL.SchemeIs("facetime-audio")) {
+  // iOS 10.3.2 introduced new prompts when facetime: and facetime-audio:
+  // URL schemes are opened. It is no longer necessary for Chrome to present
+  // another prompt before the system-provided prompt.
+  if (!base::ios::IsRunningOnOrLater(10, 3, 2) && UrlHasPhoneCallScheme(gURL)) {
     // Showing an alert view immediately has a side-effect where focus is
     // taken from the UIWebView so quickly that mouseup events are lost and
     // buttons get 'stuck' in the on position. The solution is to defer
     // showing the view.
-    [self performSelector:@selector(openFaceTimePromptForURL:)
+    [self performSelector:@selector(openPromptForURL:)
                withObject:URL
                afterDelay:0.0];
     return YES;
   }
 
-  // Use telprompt instead of tel because telprompt returns user back to
-  // Chrome after phone call is completed/aborted.
-  if (gURL.SchemeIs("tel")) {
-    GURL::Replacements replacements;
-    replacements.SetSchemeStr("telprompt");
-    URL = net::NSURLWithGURL(gURL.ReplaceComponents(replacements));
-    DCHECK([[URL scheme] isEqualToString:@"telprompt"]);
-  }
-
   // Don't open external application if chrome is not active.
   if ([[UIApplication sharedApplication] applicationState] !=
       UIApplicationStateActive)