[ios] Return early if Translate is already in desired state

This change checks the current state of Translate and returns early if
the TranslateInfobarViewDelegate action methods are attempting to
execute either a translate or revert when Translate is already in that state.

Bug: 1014959, 1029120
Change-Id: Ifdbfe587f215876eb09d46a4dea41e6590b0f160
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1940171
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Peter Lee <pkl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720095}

ios/chrome/browser/translate/translate_egtest.mm

@@ -1158,6 +1158,8 @@ class FakeNetworkChangeNotifier : public net::NetworkChangeNotifier {
     [[EarlGrey
         selectElementWithMatcher:ButtonWithAccessibilityLabel(@"English")]
         performAction:grey_tap()];
+    [[EarlGrey selectElementWithMatcher:ButtonWithAccessibilityLabel(@"French")]
+        performAction:grey_tap()];
   }
 
   // Make sure that French to English translation is not automatic yet.
@@ -1211,6 +1213,9 @@ class FakeNetworkChangeNotifier : public net::NetworkChangeNotifier {
       [[EarlGrey
           selectElementWithMatcher:ButtonWithAccessibilityLabel(@"English")]
           performAction:grey_tap()];
+      [[EarlGrey
+          selectElementWithMatcher:ButtonWithAccessibilityLabel(@"French")]
+          performAction:grey_tap()];
     }
     // Tap the notification snackbar's "UNDO" button.
     [[EarlGrey selectElementWithMatcher:UndoButton()] performAction:grey_tap()];

ios/chrome/browser/translate/translate_infobar_controller.mm

@@ -147,6 +147,9 @@ const char kTranslationCountHistogram[] =
 
 - (void)translateInfobarViewDidTapSourceLangugage:
     (TranslateInfobarView*)sender {
+  // If already showing original language, no need to revert translate.
+  if (sender.state == TranslateInfobarViewStateBeforeTranslate)
+    return;
   if ([self shouldIgnoreUserInteraction])
     return;
 
@@ -161,6 +164,9 @@ const char kTranslationCountHistogram[] =
 
 - (void)translateInfobarViewDidTapTargetLangugage:
     (TranslateInfobarView*)sender {
+  // If already showing target language, no need to translate.
+  if (sender.state == TranslateInfobarViewStateAfterTranslate)
+    return;
   if ([self shouldIgnoreUserInteraction])
     return;