Fix caret paint invalidation issues

third_party/WebKit/Source/core/editing/CaretDisplayItemClient.h

Index: third_party/WebKit/Source/core/editing/CaretDisplayItemClient.h
diff --git a/third_party/WebKit/Source/core/editing/CaretDisplayItemClient.h b/third_party/WebKit/Source/core/editing/CaretDisplayItemClient.h
index 576381e0f7a23dae49da8521e18c93c24bd8a043..742a3c453cdbd002185f2a691a8d152fd35eb026 100644
--- a/third_party/WebKit/Source/core/editing/CaretDisplayItemClient.h
+++ b/third_party/WebKit/Source/core/editing/CaretDisplayItemClient.h
@@ -74,10 +74,8 @@ class CaretDisplayItemClient final : public DisplayItemClient {
   void updateStyleAndLayoutIfNeeded(const PositionWithAffinity& caretPosition);
 
   // Called during LayoutBlock paint invalidation.
-  void invalidatePaintIfNeeded(
-      const LayoutBlock&,
-      const PaintInvalidatorContext&,
-      PaintInvalidationReason layoutBlockPaintInvalidationReason);

[Xianzhu, 2017/03/08 19:38:22]

This parameter is removed because it just indicates the reason of the
layoutBlock's display item client invalidation reason, not the raster
invalidation reason. We used the parameter to skip caret raster invalidation
which had issue of under-invalidation of raster of caret if caret is moved and
the containing block just invalidated display item client. The new test
move-caret-in-container-change-paint-offset-keep-visual.html could reproduce the
issue.

(Unrelated to this CL: I'm planning to remove the returning value of
ObjectPaintInvalidator::invalidatePaintIfNeeded() because its meaning is not
clear. Will use LayoutObject status and context at callsites instead.)

+  void invalidatePaintIfNeeded(const LayoutBlock&,
+                               const PaintInvalidatorContext&);
 
   bool shouldPaintCaret(const LayoutBlock& block) const {
     return &block == m_layoutBlock;
@@ -91,32 +89,25 @@ class CaretDisplayItemClient final : public DisplayItemClient {
   String debugName() const final;
 
  private:
-  void invalidatePaintInCurrentLayoutBlock(
-      const PaintInvalidatorContext&,
-      PaintInvalidationReason layoutBlockPaintInvalidationReason);
+  void invalidatePaintInCurrentLayoutBlock(const PaintInvalidatorContext&);
 
-  void invalidatePaintInPreviousLayoutBlock(
-      const PaintInvalidatorContext&,
-      PaintInvalidationReason layoutBlockPaintInvalidationReason);
+  void invalidatePaintInPreviousLayoutBlock(const PaintInvalidatorContext&);
 
   // These are updated by updateStyleAndLayoutIfNeeded().
   Color m_color;
   LayoutRect m_localRect;
   LayoutBlock* m_layoutBlock = nullptr;
 
-  // This is set to the previous value of m_layoutBlock during
-  // updateStyleAndLayoutIfNeeded() and can be used in invalidatePaintIfNeeded()
-  // only.
-  const LayoutBlock* m_previousLayoutBlock = nullptr;
-
   // Visual rect of the caret in m_layoutBlock. This is updated by
   // invalidatePaintIfNeeded().
   LayoutRect m_visualRect;
 
-  // This is set to the previous value of m_visualRect during
-  // updateStyleAndLayoutIfNeeded() and can be used in invalidatePaintIfNeeded()
-  // only.
-  LayoutRect m_previousVisualRect;
+  // These are set to the previous value of m_layoutBlock and m_visualRect
+  // during updateStyleAndLayoutIfNeeded() if they haven't been set since the
+  // last paint invalidation. They can only be used in invalidatePaintIfNeeded()
+  // to invalidate the caret in the previous layout block.
+  const LayoutBlock* m_previousLayoutBlock = nullptr;
+  LayoutRect m_visualRectInPreviousLayoutBlock;
 
   bool m_needsPaintInvalidation = false;
 };