Add alternative method for zooming webpages

Currently, text zoom doesn't work on iPad. This experimental method
should work there.

Bug: 1061119
Change-Id: Iaad93125be9752b5d70385be39ed6414a566228b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2424142
Commit-Queue: Robbie Gibson <rkgibson@google.com>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811230}

chrome/browser/flag-metadata.json

@@ -4619,14 +4619,19 @@
     "owners": [ "mhochk@microsoft.com", "ericwilligers@google.com" ],
     "expiry_milestone": 89
   },
+  {
+    "name": "webpage-alternative-text-zoom",
+    "owners": [ "rkgibson@google.com", "bling-flags@google.com" ],
+    "expiry_milestone": 86
+  },
   {
     "name": "webpage-default-zoom-from-dynamic-type",
-    "owners": [ "rkgibson", "bling-flags" ],
+    "owners": [ "rkgibson@google.com", "bling-flags@google.com" ],
     "expiry_milestone": 87
   },
   {
     "name": "webpage-text-accessibility",
-    "owners": [ "rkgibson", "bling-flags" ],
+    "owners": [ "rkgibson@google.com", "bling-flags@google.com" ],
     "expiry_milestone": 86
   },
   {

ios/chrome/browser/flags/about_flags.mm

@@ -365,6 +365,10 @@ const flags_ui::FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kWebPageTextAccessibilityName,
      flag_descriptions::kWebPageTextAccessibilityDescription, flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(web::kWebPageTextAccessibility)},
+    {"webpage-alternative-text-zoom",
+     flag_descriptions::kWebPageAlternativeTextZoomName,
+     flag_descriptions::kWebPageAlternativeTextZoomDescription,
+     flags_ui::kOsIos, FEATURE_VALUE_TYPE(web::kWebPageAlternativeTextZoom)},
     {"toolbar-container", flag_descriptions::kToolbarContainerName,
      flag_descriptions::kToolbarContainerDescription, flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(toolbar_container::kToolbarContainerEnabled)},

ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc

@@ -510,6 +510,11 @@ const char kWebPageTextAccessibilityDescription[] =
     "When enabled, text in web pages will respect the user's Dynamic Type "
     "setting.";
 
+const char kWebPageAlternativeTextZoomName[] =
+    "Use different method for zooming web pages";
+const char kWebPageAlternativeTextZoomDescription[] =
+    "When enabled, switches the method used to zoom web pages.";
+
 const char kWellKnownChangePasswordName[] =
     "Support for .well-known/change-password";
 const char kWellKnownChangePasswordDescription[] =

ios/chrome/browser/flags/ios_chrome_flag_descriptions.h

@@ -453,6 +453,11 @@ extern const char kWebPageDefaultZoomFromDynamicTypeDescription[];
 extern const char kWebPageTextAccessibilityName[];
 extern const char kWebPageTextAccessibilityDescription[];
 
+// Title and description for the flag to enable a different method of zooming
+// web pages.
+extern const char kWebPageAlternativeTextZoomName[];
+extern const char kWebPageAlternativeTextZoomDescription[];
+
 extern const char kWellKnownChangePasswordName[];
 extern const char kWellKnownChangePasswordDescription[];
 

ios/chrome/browser/web/BUILD.gn

@@ -57,6 +57,7 @@ source_set("web") {
     "//ios/components/ui_util",
     "//ios/components/webui:url_constants",
     "//ios/net",
+    "//ios/public/provider/chrome/browser:browser",
     "//ios/web",
     "//ios/web/common",
     "//ios/web/public/js_messaging",

ios/chrome/browser/web/features.cc

@@ -12,6 +12,9 @@ const base::Feature kWebPageTextAccessibility{"WebPageTextAccessibility",
 const base::Feature kWebPageDefaultZoomFromDynamicType{
     "WebPageDefaultZoomFromDynamicType", base::FEATURE_DISABLED_BY_DEFAULT};
 
+const base::Feature kWebPageAlternativeTextZoom{
+    "WebPageAlternativeTextZoom", base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kMobileGoogleSRP{"MobileGoogleSRP",
                                      base::FEATURE_DISABLED_BY_DEFAULT};
 

ios/chrome/browser/web/features.h

@@ -17,6 +17,9 @@ extern const base::Feature kWebPageTextAccessibility;
 // dynamic type setting.
 extern const base::Feature kWebPageDefaultZoomFromDynamicType;
 
+// Used to enable a different method of zooming web pages.
+extern const base::Feature kWebPageAlternativeTextZoom;
+
 // Feature flag to keep the mobile version for Google SRP. Should be used when
 // the desktop version is requested by default.
 extern const base::Feature kMobileGoogleSRP;

ios/chrome/browser/web/font_size_tab_helper.mm

@@ -22,6 +22,8 @@
 #include "ios/chrome/browser/pref_names.h"
 #include "ios/chrome/browser/web/features.h"
 #include "ios/components/ui_util/dynamic_type_util.h"
+#include "ios/public/provider/chrome/browser/chrome_browser_provider.h"
+#import "ios/public/provider/chrome/browser/text_zoom_provider.h"
 #include "ios/web/public/js_messaging/web_frame.h"
 #include "ios/web/public/js_messaging/web_frame_util.h"
 #include "ios/web/public/js_messaging/web_frames_manager.h"
@@ -138,12 +140,9 @@ void FontSizeTabHelper::SetPageFontSize(int size) {
     return;
   }
   tab_helper_has_zoomed_ = true;
-  std::vector<base::Value> parameters;
-  parameters.push_back(base::Value(size));
-  for (web::WebFrame* frame :
-       web_state_->GetWebFramesManager()->GetAllWebFrames()) {
-    frame->CallJavaScriptFunction("accessibility.adjustFontSize", parameters);
-  }
+
+  ios::GetChromeBrowserProvider()->GetTextZoomProvider()->SetPageFontSize(
+      web_state_, size);
 }
 
 void FontSizeTabHelper::UserZoom(Zoom zoom) {

ios/public/provider/chrome/browser/BUILD.gn

@@ -15,12 +15,15 @@ source_set("browser") {
     "geolocation_updater_provider.mm",
     "overrides_provider.h",
     "overrides_provider.mm",
+    "text_zoom_provider.h",
+    "text_zoom_provider.mm",
   ]
   deps = [
     "//base",
     "//components/metrics",
     "//ios/public/provider/chrome/browser/mailto",
     "//ios/web/public",
+    "//ios/web/public/js_messaging",
     "//url",
   ]
   frameworks = [ "CoreLocation.framework" ]

ios/public/provider/chrome/browser/chrome_browser_provider.h

@@ -26,6 +26,7 @@ class MailtoHandlerProvider;
 class OmahaServiceProvider;
 class OverridesProvider;
 class SpotlightProvider;
+class TextZoomProvider;
 class UserFeedbackProvider;
 class VoiceSearchProvider;
 
@@ -180,6 +181,8 @@ class ChromeBrowserProvider {
   // Returns an instance of the DiscoverFeed provider;
   virtual DiscoverFeedProvider* GetDiscoverFeedProvider() const;
 
+  virtual TextZoomProvider* GetTextZoomProvider() const;
+
   // Adds and removes observers.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
@@ -191,6 +194,7 @@ class ChromeBrowserProvider {
  private:
   base::ObserverList<Observer, true>::Unchecked observer_list_;
   std::unique_ptr<MailtoHandlerProvider> mailto_handler_provider_;
+  std::unique_ptr<TextZoomProvider> text_zoom_provider_;
 };
 
 }  // namespace ios

ios/public/provider/chrome/browser/chrome_browser_provider.mm

@@ -8,6 +8,7 @@
 
 #include "components/metrics/metrics_provider.h"
 #import "ios/public/provider/chrome/browser/mailto/mailto_handler_provider.h"
+#import "ios/public/provider/chrome/browser/text_zoom_provider.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
@@ -30,7 +31,8 @@ ChromeBrowserProvider* GetChromeBrowserProvider() {
 // A dummy implementation of ChromeBrowserProvider.
 
 ChromeBrowserProvider::ChromeBrowserProvider()
-    : mailto_handler_provider_(std::make_unique<MailtoHandlerProvider>()) {}
+    : mailto_handler_provider_(std::make_unique<MailtoHandlerProvider>()),
+      text_zoom_provider_(std::make_unique<TextZoomProvider>()) {}
 
 ChromeBrowserProvider::~ChromeBrowserProvider() {
   for (auto& observer : observer_list_)
@@ -149,6 +151,10 @@ BrandedImageProvider* ChromeBrowserProvider::GetBrandedImageProvider() const {
   return nullptr;
 }
 
+TextZoomProvider* ChromeBrowserProvider::GetTextZoomProvider() const {
+  return text_zoom_provider_.get();
+}
+
 void ChromeBrowserProvider::HideModalViewStack() const {}
 
 void ChromeBrowserProvider::LogIfModalViewsArePresented() const {}

ios/public/provider/chrome/browser/text_zoom_provider.h

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IOS_PUBLIC_PROVIDER_CHROME_BROWSER_TEXT_ZOOM_PROVIDER_H_
+#define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_TEXT_ZOOM_PROVIDER_H_
+
+namespace web {
+class WebState;
+}
+
+class TextZoomProvider {
+ public:
+  TextZoomProvider();
+  virtual ~TextZoomProvider();
+
+  // Zooms the given web_state to the provided size as a percentage. I.e. a size
+  // of 100 corresponds to a zoom of 100%.
+  virtual void SetPageFontSize(web::WebState* web_state, int size);
+
+ protected:
+  // Uses injected javascript to change to zoom the page font size to the given
+  // |size| as a percentage (size = 100 -> 100% zoom).
+  void SetPageFontSizeJavascript(web::WebState* web_state, int size);
+};
+
+#endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_TEXT_ZOOM_PROVIDER_H_

ios/public/provider/chrome/browser/text_zoom_provider.mm

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/public/provider/chrome/browser/text_zoom_provider.h"
+
+#import "base/values.h"
+#include "ios/web/public/js_messaging/web_frame.h"
+#include "ios/web/public/js_messaging/web_frames_manager.h"
+#import "ios/web/public/web_state.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+TextZoomProvider::TextZoomProvider() = default;
+
+TextZoomProvider::~TextZoomProvider() = default;
+
+void TextZoomProvider::SetPageFontSize(web::WebState* web_state, int size) {
+  SetPageFontSizeJavascript(web_state, size);
+}
+
+void TextZoomProvider::SetPageFontSizeJavascript(web::WebState* web_state,
+                                                 int size) {
+  std::vector<base::Value> parameters;
+  parameters.push_back(base::Value(size));
+  for (web::WebFrame* frame :
+       web_state->GetWebFramesManager()->GetAllWebFrames()) {
+    frame->CallJavaScriptFunction("accessibility.adjustFontSize", parameters);
+  }
+}