Fix gradient background invalidation when HTML size changes

third_party/WebKit/Source/core/paint/ViewPaintInvalidator.h

Index: third_party/WebKit/Source/core/paint/ViewPaintInvalidator.h
diff --git a/third_party/WebKit/Source/core/paint/ViewPaintInvalidator.h b/third_party/WebKit/Source/core/paint/ViewPaintInvalidator.h
new file mode 100644
index 0000000000000000000000000000000000000000..4684d1be78566f001cd475aa6689227b23411721
--- /dev/null
+++ b/third_party/WebKit/Source/core/paint/ViewPaintInvalidator.h
@@ -0,0 +1,35 @@
+// Copyright 2017 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 ViewPaintInvalidator_h
+#define ViewPaintInvalidator_h
+
+#include "platform/graphics/PaintInvalidationReason.h"
+#include "wtf/Allocator.h"
+
+namespace blink {
+
+class LayoutView;
+struct PaintInvalidatorContext;
+
+class ViewPaintInvalidator {
+  STACK_ALLOCATED();
+
+ public:
+  ViewPaintInvalidator(const LayoutView& view,
+                       const PaintInvalidatorContext& context)
+      : m_view(view), m_context(context) {}
+
+  PaintInvalidationReason invalidatePaintIfNeeded();
+
+ private:
+  void invalidateBackgroundIfNeeded();
+
+  const LayoutView& m_view;
+  const PaintInvalidatorContext& m_context;
+};
+
+}  // namespace blink
+
+#endif