Cursor Control: Register listener for content editable element

In this CL, we register listener for content editable element
including <input> and <textarea> elements.

This is used to notify that the browser side that there will be a
handler for touchstart event, so it needs to send the event to the
renderer.

Please refer to the bug for more information about the overall design.

Bug: 1126778
Change-Id: I35457d5f1ca02c943b5bf594c06a6a70e2c6e3bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2401786
Commit-Queue: Shimi Zhang <ctzsm@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808475}

third_party/blink/renderer/core/css/resolver/style_adjuster.cc

@@ -38,6 +38,7 @@
 #include "third_party/blink/renderer/core/dom/element.h"
 #include "third_party/blink/renderer/core/dom/node_computed_style.h"
 #include "third_party/blink/renderer/core/dom/shadow_root.h"
+#include "third_party/blink/renderer/core/frame/event_handler_registry.h"
 #include "third_party/blink/renderer/core/frame/local_frame.h"
 #include "third_party/blink/renderer/core/frame/local_frame_view.h"
 #include "third_party/blink/renderer/core/frame/settings.h"
@@ -65,6 +66,7 @@
 #include "third_party/blink/renderer/platform/runtime_enabled_features.h"
 #include "third_party/blink/renderer/platform/transforms/transform_operations.h"
 #include "third_party/blink/renderer/platform/wtf/assertions.h"
+#include "ui/base/ui_base_features.h"
 
 namespace blink {
 
@@ -74,6 +76,22 @@ bool IsOverflowClipOrVisible(EOverflow overflow) {
   return overflow == EOverflow::kClip || overflow == EOverflow::kVisible;
 }
 
+bool IsEditableElement(Element* element, const ComputedStyle& style) {
+  if (style.UserModify() != EUserModify::kReadOnly)
+    return true;
+
+  if (!element)
+    return false;
+
+  if (auto* textarea = DynamicTo<HTMLTextAreaElement>(*element))
+    return !textarea->IsDisabledOrReadOnly();
+
+  if (auto* input = DynamicTo<HTMLInputElement>(*element))
+    return !input->IsDisabledOrReadOnly() && input->IsTextField();
+
+  return false;
+}
+
 TouchAction AdjustTouchActionForElement(TouchAction touch_action,
                                         const ComputedStyle& style,
                                         Element* element) {
@@ -571,6 +589,13 @@ static void AdjustEffectiveTouchAction(ComputedStyle& style,
   TouchAction enforced_by_policy = TouchAction::kNone;
   if (element->GetDocument().IsVerticalScrollEnforced())
     enforced_by_policy = TouchAction::kPanY;
+  if (base::FeatureList::IsEnabled(::features::kSwipeToMoveCursor) &&
+      IsEditableElement(element, style)) {
+    EventHandlerRegistry& registry =
+        element->GetDocument().GetFrame()->GetEventHandlerRegistry();
+    registry.DidAddEventHandler(
+        *element, EventHandlerRegistry::kTouchStartOrMoveEventBlocking);
+  }
 
   // Apply the adjusted parent effective touch actions.
   style.SetEffectiveTouchAction((element_touch_action & inherited_action) |

third_party/blink/renderer/core/css/resolver/style_adjuster_test.cc

@@ -2,10 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "base/test/scoped_feature_list.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/blink/renderer/core/dom/node_computed_style.h"
+#include "third_party/blink/renderer/core/frame/event_handler_registry.h"
 #include "third_party/blink/renderer/core/testing/core_unit_test_helper.h"
 #include "third_party/blink/renderer/platform/testing/runtime_enabled_features_test_helpers.h"
+#include "ui/base/ui_base_features.h"
 
 namespace blink {
 
@@ -158,4 +161,76 @@ TEST_F(StyleAdjusterTest, AdjustOverflow) {
   EXPECT_EQ(EOverflow::kAuto, target->GetComputedStyle()->OverflowY());
 }
 
+TEST_F(StyleAdjusterTest, SetListenerForContentEditableArea) {
+  base::test::ScopedFeatureList feature_list;
+  feature_list.InitWithFeatures({::features::kSwipeToMoveCursor}, {});
+  ASSERT_TRUE(base::FeatureList::IsEnabled(::features::kSwipeToMoveCursor));
+
+  GetDocument().SetBaseURLOverride(KURL("http://test.com"));
+  SetBodyInnerHTML(R"HTML(
+    <div id='target' contenteditable='false'></div>
+  )HTML");
+  UpdateAllLifecyclePhasesForTest();
+
+  EventHandlerRegistry& registry =
+      GetDocument().GetFrame()->GetEventHandlerRegistry();
+
+  Element* target = GetDocument().getElementById("target");
+  EXPECT_FALSE(registry.HasEventHandlers(
+      EventHandlerRegistry::kTouchStartOrMoveEventBlocking));
+
+  target->setAttribute(html_names::kContenteditableAttr, "true");
+  UpdateAllLifecyclePhasesForTest();
+  EXPECT_TRUE(registry.HasEventHandlers(
+      EventHandlerRegistry::kTouchStartOrMoveEventBlocking));
+}
+
+TEST_F(StyleAdjusterTest, SetListenerForInputElement) {
+  base::test::ScopedFeatureList feature_list;
+  feature_list.InitWithFeatures({::features::kSwipeToMoveCursor}, {});
+  ASSERT_TRUE(base::FeatureList::IsEnabled(::features::kSwipeToMoveCursor));
+
+  GetDocument().SetBaseURLOverride(KURL("http://test.com"));
+  SetBodyInnerHTML(R"HTML(
+    <input type="text" id='target' disabled>
+  )HTML");
+  UpdateAllLifecyclePhasesForTest();
+
+  EventHandlerRegistry& registry =
+      GetDocument().GetFrame()->GetEventHandlerRegistry();
+
+  Element* target = GetDocument().getElementById("target");
+  EXPECT_FALSE(registry.HasEventHandlers(
+      EventHandlerRegistry::kTouchStartOrMoveEventBlocking));
+
+  target->removeAttribute(html_names::kDisabledAttr);
+  UpdateAllLifecyclePhasesForTest();
+  EXPECT_TRUE(registry.HasEventHandlers(
+      EventHandlerRegistry::kTouchStartOrMoveEventBlocking));
+}
+
+TEST_F(StyleAdjusterTest, SetListenerForTextAreaElement) {
+  base::test::ScopedFeatureList feature_list;
+  feature_list.InitWithFeatures({::features::kSwipeToMoveCursor}, {});
+  ASSERT_TRUE(base::FeatureList::IsEnabled(::features::kSwipeToMoveCursor));
+
+  GetDocument().SetBaseURLOverride(KURL("http://test.com"));
+  SetBodyInnerHTML(R"HTML(
+    <textarea id="target" readonly></textarea>
+  )HTML");
+  UpdateAllLifecyclePhasesForTest();
+
+  EventHandlerRegistry& registry =
+      GetDocument().GetFrame()->GetEventHandlerRegistry();
+
+  Element* target = GetDocument().getElementById("target");
+  EXPECT_FALSE(registry.HasEventHandlers(
+      EventHandlerRegistry::kTouchStartOrMoveEventBlocking));
+
+  target->removeAttribute(html_names::kReadonlyAttr);
+  UpdateAllLifecyclePhasesForTest();
+  EXPECT_TRUE(registry.HasEventHandlers(
+      EventHandlerRegistry::kTouchStartOrMoveEventBlocking));
+}
+
 }  // namespace blink

ui/base/ui_base_features.cc

@@ -255,4 +255,7 @@ const char kPredictorNameEmpty[] = "empty";
 const char kFilterNameEmpty[] = "empty_filter";
 const char kFilterNameOneEuro[] = "one_euro_filter";
 
+const base::Feature kSwipeToMoveCursor{"SwipeToMoveCursor",
+                                       base::FEATURE_DISABLED_BY_DEFAULT};
+
 }  // namespace features

ui/base/ui_base_features.h

@@ -142,6 +142,10 @@ COMPONENT_EXPORT(UI_BASE_FEATURES) extern const char kPredictorNameEmpty[];
 COMPONENT_EXPORT(UI_BASE_FEATURES) extern const char kFilterNameEmpty[];
 COMPONENT_EXPORT(UI_BASE_FEATURES) extern const char kFilterNameOneEuro[];
 
+// Android only feature, for swipe to move cursor.
+COMPONENT_EXPORT(UI_BASE_FEATURES)
+extern const base::Feature kSwipeToMoveCursor;
+
 }  // namespace features
 
 #endif  // UI_BASE_UI_BASE_FEATURES_H_