Refactor DrawingRecorders to check for cached drawings earlier

Source/web/WebFontImpl.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 81 matching lines @@
     FontCachePurgePreventer fontCachePurgePreventer;
     FloatRect textClipRect(clip);
     TextRun textRun(run);
     TextRunPaintInfo runInfo(textRun);
     runInfo.bounds = textClipRect;
 
     IntRect intRect(clip);
     SkPictureBuilder pictureBuilder(intRect);
     GraphicsContext* context = &pictureBuilder.context();
 
-    {
+    if (!DrawingRecorder::useCachedDrawingIfPossible(*context, *this, DisplayItem::WebFont)) {

[Xianzhu, 2015/07/03 01:24:42]

Nit: Another similar place still uses ASSERT. Better to keep consistence.

[pdr., 2015/07/03 02:38:05]

Good catch. Fixed.

         DrawingRecorder drawingRecorder(*context, *this, DisplayItem::WebFont, intRect);
-        ASSERT(!drawingRecorder.canUseCachedDrawing());
         context->save();
         context->setFillColor(color);
         context->clip(textClipRect);
         context->drawText(m_font, runInfo, leftBaseline);
         context->restore();
     }
 
     pictureBuilder.endRecording()->playback(canvas);
 }
 
 int WebFontImpl::calculateWidth(const WebTextRun& run) const
 {
     return m_font.width(run, 0);
 }
 
 int WebFontImpl::offsetForPosition(const WebTextRun& run, float position) const
 {
     return m_font.offsetForPosition(run, position, true);
 }
 
 WebFloatRect WebFontImpl::selectionRectForText(const WebTextRun& run, const WebFloatPoint& leftBaseline, int height, int from, int to) const
 {
     return m_font.selectionRectForText(run, leftBaseline, height, from, to);
 }
 
 } // namespace blink