GC::saveLayer() may taint the current clip.

Source/platform/graphics/GraphicsContext.cpp

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
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@@ skipping 161 matching lines @@
         m_paintStateIndex--;
         m_paintState = m_paintStateStack[m_paintStateIndex].get();
     }
 
     CanvasSaveState savedState = m_canvasStateStack.last();
     m_canvasStateStack.removeLast();
     m_canvasSaveFlags = savedState.m_flags;
     m_canvas->restoreToCount(savedState.m_restoreCount);
 }
 
-void GraphicsContext::saveLayer(const SkRect* bounds, const SkPaint* paint, SkCanvas::SaveFlags saveFlags)
+void GraphicsContext::saveLayer(const SkRect* bounds, const SkPaint* paint,
+    SkCanvas::SaveFlags extraFlags)
 {
     if (paintingDisabled())
         return;
 
     realizeCanvasSave(SkCanvas::kMatrixClip_SaveFlag);
 
-    m_canvas->saveLayer(bounds, paint, saveFlags);
+    // Always save the clip & matrix.
+    SkCanvas::SaveFlags flags = static_cast<SkCanvas::SaveFlags>(
+        SkCanvas::kMatrixClip_SaveFlag | extraFlags);

[Stephen White, 2014/03/26 17:45:52]

Just an idea, but we could probably set these in the flags passed by
beginLayer() instead of here. The only calls to saveLayer() I can see other than
beginLayer() are from FEGaussianBlur and FEMorphology, which use the default arg
of kARGB_ClipLayer_SaveFlag anyway, which already includes matrix & clip. (Those
two should probably be calling beginLayer() anyway, then we can make saveLayer()
private.) Anyway, all that can be done in another patch.

[f(malita), 2014/03/26 19:31:28]

Done.

+    m_canvas->saveLayer(bounds, paint, flags);
+
     if (bounds)
         m_canvas->clipRect(*bounds);
     if (m_trackOpaqueRegion)
         m_opaqueRegion.pushCanvasLayer(paint);
 }
 
 void GraphicsContext::restoreLayer()
 {
     if (paintingDisabled())
         return;
@@ skipping 1685 matching lines @@
 
 void GraphicsContext::didDrawTextInRect(const SkRect& textRect)
 {
     if (m_trackTextRegion) {
         TRACE_EVENT0("skia", "PlatformContextSkia::trackTextRegion");
         m_textRegion.join(textRect);
     }
 }
 
 }