Make stream captures work on canvases that are not in the DOM.

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

 /*
  * Copyright (C) 2009 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1371 matching lines @@
 
   if (!drawingBuffer()->markContentsChanged() && m_markedCanvasDirty) {
     return;
   }
 
   if (!canvas())
     return;
 
   LayoutBox* layoutBox = canvas()->layoutBox();
   if (layoutBox && layoutBox->hasAcceleratedCompositing()) {
+    layoutBox->contentChanged(changeType);
+  }
+  if (!m_markedCanvasDirty) {
     m_markedCanvasDirty = true;
-    canvas()->clearCopiedImage();

[xlai (Olivia), 2017/02/08 17:58:40]

Why is this removed?

[Justin Novosad, 2017/02/08 18:43:12]

Because it was already being called by HTMLCanvasElement::didDraw

-    layoutBox->contentChanged(changeType);
-  } else {
-    if (!m_markedCanvasDirty) {
-      m_markedCanvasDirty = true;
-      canvas()->didDraw(
-          FloatRect(FloatPoint(0, 0), FloatSize(clampedCanvasSize())));
-    }
+    IntSize canvasSize = clampedCanvasSize();
+    didDraw(SkIRect::MakeXYWH(0, 0, canvasSize.width(), canvasSize.height()));
   }
 }
 
 void WebGLRenderingContextBase::onErrorMessage(const char* message,
                                                int32_t id) {
   if (m_synthesizedErrorsToConsole)
     printGLErrorToConsole(message);
   InspectorInstrumentation::didFireWebGLErrorOrWarning(canvas(), message);
 }
 
@@ skipping 6427 matching lines @@
 
 void WebGLRenderingContextBase::getHTMLOrOffscreenCanvas(
     HTMLCanvasElementOrOffscreenCanvas& result) const {
   if (canvas())
     result.setHTMLCanvasElement(canvas());
   else
     result.setOffscreenCanvas(offscreenCanvas());
 }
 
 }  // namespace blink