[SH-iOS] Disable LinkToText For PDF Documents

Prevent showing the Link-to-text action when the current page is not
HTML and also when, for some reason, the main frame cannot execute
JavaScript.

Bug: 1157053
Change-Id: I11702dd3d91d204b9b80f686c29ac4640c84ea88
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2585836
Commit-Queue: Sebastien Lalancette <seblalancette@chromium.org>
Commit-Queue: sebsg <sebsg@chromium.org>
Reviewed-by: sebsg <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836129}

ios/chrome/browser/link_to_text/link_to_text_tab_helper.mm

@@ -41,10 +41,15 @@ void LinkToTextTabHelper::CreateForWebState(web::WebState* web_state) {
 
 bool LinkToTextTabHelper::ShouldOffer() {
   // TODO(crbug.com/1134708): add more checks, like text only.
-  return true;
+  web::WebFrame* main_frame =
+      web_state_->GetWebFramesManager()->GetMainWebFrame();
+  return web_state_->ContentIsHTML() && main_frame &&
+         main_frame->CanCallJavaScriptFunction();
 }
 
 void LinkToTextTabHelper::GetLinkToText(LinkToTextCallback callback) {
+  DCHECK(ShouldOffer());
+
   link_generation_timer_ = std::make_unique<base::ElapsedTimer>();
 
   base::WeakPtr<LinkToTextTabHelper> weak_ptr = weak_ptr_factory_.GetWeakPtr();

ios/chrome/browser/ui/link_to_text/link_to_text_mediator_unittest.mm

@@ -192,11 +192,28 @@ class LinkToTextMediatorTest : public PlatformTest {
   id mocked_consumer_;
 };
 
-// Tests that the mediator should, currently, always offer link to text.
+// Tests that the mediator should offer link to text to HTML pages that can
+// call JavaScript functions.
 TEST_F(LinkToTextMediatorTest, ShouldOfferLinkToText) {
+  // By default, all fake instances return the right values.
   EXPECT_TRUE([mediator_ shouldOfferLinkToText]);
 }
 
+// Tests that the mediator should not offer link to text to pages that are not
+// HTML.
+TEST_F(LinkToTextMediatorTest, ShouldNotOfferLinkToTextNotHTML) {
+  web_state_->SetContentIsHTML(false);
+  EXPECT_FALSE([mediator_ shouldOfferLinkToText]);
+}
+
+// Tests that the mediator should not offer link to text when, for some reason,
+// the main frame cannot call JavaScript functions.
+TEST_F(LinkToTextMediatorTest,
+       ShouldNotOfferLinkToTextCannotExecuteJavaScript) {
+  main_frame_->set_can_call_function(false);
+  EXPECT_FALSE([mediator_ shouldOfferLinkToText]);
+}
+
 // Tests that the shareHighlight command is triggered with the right parameters
 // when the view is not zoomed in.
 TEST_F(LinkToTextMediatorTest, HandleLinkToTextSelectionTriggersCommandNoZoom) {