"Find" scrolling should be smoothly animated.

third_party/WebKit/Source/core/editing/Editor.cpp

Index: third_party/WebKit/Source/core/editing/Editor.cpp
diff --git a/third_party/WebKit/Source/core/editing/Editor.cpp b/third_party/WebKit/Source/core/editing/Editor.cpp
index e31a15ba917ac60211ce405a3072e80fae1ad9d7..47f6887bf0b08ca507983807103645a681f3064c 100644
--- a/third_party/WebKit/Source/core/editing/Editor.cpp
+++ b/third_party/WebKit/Source/core/editing/Editor.cpp
@@ -1615,10 +1615,26 @@ Range* Editor::FindStringAndScrollToVisible(const String& target,
     return nullptr;
 
   Node* first_node = next_match->FirstNode();
-  first_node->GetLayoutObject()->ScrollRectToVisible(
-      LayoutRect(next_match->BoundingBox()),
-      ScrollAlignment::kAlignCenterIfNeeded,
-      ScrollAlignment::kAlignCenterIfNeeded, kUserScroll);

[sunyunjia, 2017/06/12 21:17:57]

Not sure why this was kUserScroll. Perhaps we should also change it to
kProgrammaticScroll?

[bokan, 2017/06/13 01:48:08]

Acknowledged.

+  first_node->GetDocument()

[bokan, 2017/06/13 01:48:08]

This leaks too many details of how smooth scroll are implemented. Lets rearrange
LayoutBox::ScrollRectToVisible a little; move the current implementation into
ScrollRectToVisibleRecursive and call it from ScrollRectToVisible.
LayoutBox::ScrollRectToVisible should call Abort and RunQueuedAnimations if the
scroll is smooth. 

[sunyunjia, 2017/06/13 17:45:11]

Done.

+      .GetPage()
+      ->GetSmoothScrollSequencer()
+      ->AbortAnimations();
+  if (RuntimeEnabledFeatures::CSSOMSmoothScrollEnabled()) {

[bokan, 2017/06/13 01:48:08]

This has no web-facing consequences so there's no need to guard it behind the
flag. Lets just make this smooth in all cases.

[sunyunjia, 2017/06/13 17:45:11]

Done.

+    first_node->GetLayoutObject()->ScrollRectToVisible(
+        LayoutRect(next_match->BoundingBox()),
+        ScrollAlignment::kAlignCenterIfNeeded,
+        ScrollAlignment::kAlignCenterIfNeeded, kProgrammaticScroll, true,
+        kScrollBehaviorSmooth);
+    first_node->GetDocument()
+        .GetPage()
+        ->GetSmoothScrollSequencer()
+        ->RunQueuedAnimations();
+  } else {
+    first_node->GetLayoutObject()->ScrollRectToVisible(
+        LayoutRect(next_match->BoundingBox()),
+        ScrollAlignment::kAlignCenterIfNeeded,
+        ScrollAlignment::kAlignCenterIfNeeded, kUserScroll);
+  }
   first_node->GetDocument().SetSequentialFocusNavigationStartingPoint(
       first_node);