[iOS] Only enable text zoom on pages with HTML content

The text zoom option should only be enabled on pages with HTML content,
as the zoom mechanism uses Javascript.

Bug: 1062101
Change-Id: Ia2285d73adf5b82fb28c348e49c16b4453a707c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2106191
Commit-Queue: Robbie Gibson <rkgibson@google.com>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751303}

ios/chrome/browser/ui/popup_menu/popup_menu_mediator.mm

@@ -652,7 +652,7 @@ PopupMenuToolsItem* CreateTableViewItem(int titleID,
 
 // Whether or not text zoom is enabled
 - (BOOL)isTextZoomEnabled {
-  if (self.webContentAreaShowingOverlay || ![self isCurrentURLWebURL]) {
+  if (self.webContentAreaShowingOverlay) {
     return NO;
   }
 
@@ -660,7 +660,8 @@ PopupMenuToolsItem* CreateTableViewItem(int titleID,
     return NO;
   }
   FontSizeTabHelper* helper = FontSizeTabHelper::FromWebState(self.webState);
-  return helper && !helper->IsTextZoomUIActive();
+  return helper && helper->CurrentPageSupportsTextZoom() &&
+         !helper->IsTextZoomUIActive();
 }
 
 // Whether the page is currently loading.

ios/chrome/browser/web/font_size_tab_helper.h

@@ -55,6 +55,9 @@ class FontSizeTabHelper : public web::WebStateObserver,
   // not the UI should be displayed when possible.
   void SetTextZoomUIActive(bool active);
 
+  // Text zoom is currently only supported on HTML pages.
+  bool CurrentPageSupportsTextZoom() const;
+
   // Remove any stored zoom levels from the provided |PrefService|.
   static void ClearUserZoomPrefs(PrefService* pref_service);
 

ios/chrome/browser/web/font_size_tab_helper.mm

@@ -126,6 +126,9 @@ void FontSizeTabHelper::ClearUserZoomPrefs(PrefService* pref_service) {
 }
 
 void FontSizeTabHelper::SetPageFontSize(int size) {
+  if (!CurrentPageSupportsTextZoom()) {
+    return;
+  }
   tab_helper_has_zoomed_ = true;
   if (web_state_->ContentIsHTML()) {
     NSString* js = [NSString
@@ -135,6 +138,7 @@ void FontSizeTabHelper::SetPageFontSize(int size) {
 }
 
 void FontSizeTabHelper::UserZoom(Zoom zoom) {
+  DCHECK(CurrentPageSupportsTextZoom());
   double new_zoom_multiplier = NewMultiplierAfterZoom(zoom).value_or(1);
   StoreCurrentUserZoomMultiplier(new_zoom_multiplier);
 
@@ -206,6 +210,10 @@ void FontSizeTabHelper::SetTextZoomUIActive(bool active) {
   text_zoom_ui_active_ = active;
 }
 
+bool FontSizeTabHelper::CurrentPageSupportsTextZoom() const {
+  return web_state_->ContentIsHTML();
+}
+
 int FontSizeTabHelper::GetFontSize() const {
   // Multiply by 100 as the web property needs a percentage.
   return SystemSuggestedFontSizeMultiplier() * GetCurrentUserZoomMultiplier() *

ios/chrome/browser/web/font_size_tab_helper_unittest.mm

@@ -277,3 +277,15 @@ TEST_F(FontSizeTabHelperTest, ClearUserZoomPrefs) {
                   ->Get(prefs::kIosUserZoomMultipliers)
                   ->DictEmpty());
 }
+
+// Tests that zoom is only enabled if the page content is html.
+TEST_F(FontSizeTabHelperTest, CanZoomContent) {
+  FontSizeTabHelper* font_size_tab_helper =
+      FontSizeTabHelper::FromWebState(&web_state_);
+
+  web_state_.SetContentIsHTML(false);
+  EXPECT_FALSE(font_size_tab_helper->CurrentPageSupportsTextZoom());
+
+  web_state_.SetContentIsHTML(true);
+  EXPECT_TRUE(font_size_tab_helper->CurrentPageSupportsTextZoom());
+}