Reduce canonicalization when dragging

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

Index: third_party/WebKit/Source/core/editing/SelectionEditor.cpp
diff --git a/third_party/WebKit/Source/core/editing/SelectionEditor.cpp b/third_party/WebKit/Source/core/editing/SelectionEditor.cpp
index 14f7509c4de98e7fd4807ce221e35998cc3d7757..5624733f5cd04e17b5801f9c40ccfbc052d27265 100644
--- a/third_party/WebKit/Source/core/editing/SelectionEditor.cpp
+++ b/third_party/WebKit/Source/core/editing/SelectionEditor.cpp
@@ -371,15 +371,19 @@ void SelectionEditor::updateCachedVisibleSelectionIfNeeded() const {
     return;
 
   m_cachedVisibleSelectionInDOMTree = createVisibleSelection(m_selection);
-  m_cachedVisibleSelectionInFlatTree = createVisibleSelection(
-      SelectionInFlatTree::Builder()
-          .setBaseAndExtent(toPositionInFlatTree(m_selection.base()),
-                            toPositionInFlatTree(m_selection.extent()))
-          .setAffinity(m_selection.affinity())
-          .setHasTrailingWhitespace(m_selection.hasTrailingWhitespace())
-          .setGranularity(m_selection.granularity())
-          .setIsDirectional(m_selection.isDirectional())
-          .build());
+  if (m_cachedVisibleSelectionInDOMTree.isNone()) {
+    m_cachedVisibleSelectionInFlatTree = VisibleSelectionInFlatTree();
+  } else {
+    m_cachedVisibleSelectionInFlatTree = createVisibleSelection(
+        SelectionInFlatTree::Builder()
+            .setBaseAndExtent(toPositionInFlatTree(m_selection.base()),
+                              toPositionInFlatTree(m_selection.extent()))
+            .setAffinity(m_selection.affinity())
+            .setHasTrailingWhitespace(m_selection.hasTrailingWhitespace())
+            .setGranularity(m_selection.granularity())
+            .setIsDirectional(m_selection.isDirectional())
+            .build());
+  }
   m_styleVersion = document().styleVersion();

[yosin_UTC9, 2017/03/16 06:39:18]

Could you move L387 and L388 to L373 and make L374 to early return-style to
reduce indentation and make patch size smaller.

 m_styleVersion = document().styleVersion();
 m_cacheIsDirty = false;
 m_cachedVisibleSelectionInDOMTree = createVisibleSelection(m_selection);
 if (m_cachedVisibleSelectionInDOMTree.isNone()) {
  m_cachedVisibleSelectionInFlatTree = VisibleSelectionInFlatTree();
  return;
 }
 ...

[yoichio, 2017/03/16 06:56:40]

Done.

   m_cacheIsDirty = false;
 }