Fix 2D canvas state persistency after OffscreenCanvas.transferToImageBitmap

third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.cpp

 // Copyright 2016 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.
 
 #include "modules/canvas2d/BaseRenderingContext2D.h"
 
 #include "bindings/core/v8/ExceptionMessages.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
 #include "core/css/parser/CSSParser.h"
@@ skipping 74 matching lines @@
     m_stateStack.removeLast();
     m_stateStack.last()->clearResolvedFilter();
     m_path.transform(state().transform().inverse());
     SkCanvas* c = drawingCanvas();
     if (c)
         c->restore();
 
     validateStateStack();
 }
 
+void BaseRenderingContext2D::restoreMatrixClipStack(SkCanvas* c) const
+{
+    if (!c)
+        return;
+    HeapVector<Member<CanvasRenderingContext2DState>>::const_iterator currState;
+    DCHECK(m_stateStack.begin() < m_stateStack.end());
+    for (currState = m_stateStack.begin(); currState < m_stateStack.end(); currState++) {
+        c->setMatrix(SkMatrix::I());
+        currState->get()->playbackClips(c);
+        c->setMatrix(affineTransformToSkMatrix(currState->get()->transform()));
+        c->save();
+    }
+    c->restore();
+}
+
 static inline void convertCanvasStyleToUnionType(CanvasStyle* style, StringOrCanvasGradientOrCanvasPattern& returnValue)
 {
     if (CanvasGradient* gradient = style->getCanvasGradient()) {
         returnValue.setCanvasGradient(gradient);
         return;
     }
     if (CanvasPattern* pattern = style->getCanvasPattern()) {
         returnValue.setCanvasPattern(pattern);
         return;
     }
@@ skipping 1281 matching lines @@
 
     imageBuffer()->willOverwriteCanvas();
 }
 
 DEFINE_TRACE(BaseRenderingContext2D)
 {
     visitor->trace(m_stateStack);
 }
 
 } // namespace blink