Remove the composited path from WebViewImpl::paint().

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 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 1749 matching lines @@
     // The compositor readback always gives back pixels in BGRA order, but for
     // example Android's Skia uses RGBA ordering so the red and blue channels
     // need to be swapped.
     uint8_t* pixels = reinterpret_cast<uint8_t*>(target.getPixels());
     for (size_t i = 0; i < target.getSize(); i += 4)
         std::swap(pixels[i], pixels[i + 2]);
 #endif
     canvas->writePixels(target, rect.x(), rect.y());
 }
 
-void WebViewImpl::paint(WebCanvas* canvas, const WebRect& rect, PaintOptions option)
+void WebViewImpl::paint(WebCanvas* canvas, const WebRect& rect)

[enne (OOO), 2014/05/02 23:16:23]

I do think this needs to be split into two functions for readability at least. 
If you don't want to change the public API in this patch, could you add an
internal paintAndroid and paintNonComposited (or whatever) and just have one
#ifdef?

 {
+    // Note: This method can be called on a composited WebView on OS(ANDROID)
+    // but this will hopefully be changed once the link disambiguation feature
+    // renders using the compositor.
 #if !OS(ANDROID)
-    // ReadbackFromCompositorIfAvailable is the only option available on non-Android.
-    // Ideally, Android would always use ReadbackFromCompositorIfAvailable as well.
-    ASSERT(option == ReadbackFromCompositorIfAvailable);
+    // This should only be used when compositing is not being used for this
+    // WebView, and it is painting into the recording of its parent.
+    ASSERT(!isAcceleratedCompositingActive());
 #endif
 
-    if (option == ReadbackFromCompositorIfAvailable && isAcceleratedCompositingActive()) {
-        // If a canvas was passed in, we use it to grab a copy of the
-        // freshly-rendered pixels.
-        if (canvas) {
-            // Clip rect to the confines of the rootLayerTexture.
-            IntRect resizeRect(rect);
-            resizeRect.intersect(IntRect(IntPoint(0, 0), m_layerTreeView->deviceViewportSize()));
-            doPixelReadbackToCanvas(canvas, resizeRect);
-        }
-    } else {
-        FrameView* view = page()->mainFrame()->view();
-        PaintBehavior oldPaintBehavior = view->paintBehavior();
-        if (isAcceleratedCompositingActive()) {
-            ASSERT(option == ForceSoftwareRenderingAndIgnoreGPUResidentContent);
-            view->setPaintBehavior(oldPaintBehavior | PaintBehaviorFlattenCompositingLayers);
-        }
+    FrameView* view = page()->mainFrame()->view();
+    PaintBehavior oldPaintBehavior = view->paintBehavior();
 
-        double paintStart = currentTime();
-        PageWidgetDelegate::paint(m_page.get(), pageOverlays(), canvas, rect, isTransparent() ? PageWidgetDelegate::Translucent : PageWidgetDelegate::Opaque);
-        double paintEnd = currentTime();
-        double pixelsPerSec = (rect.width * rect.height) / (paintEnd - paintStart);
-        blink::Platform::current()->histogramCustomCounts("Renderer4.SoftwarePaintDurationMS", (paintEnd - paintStart) * 1000, 0, 120, 30);
-        blink::Platform::current()->histogramCustomCounts("Renderer4.SoftwarePaintMegapixPerSecond", pixelsPerSec / 1000000, 10, 210, 30);
+    double paintStart = currentTime();
 
-        if (isAcceleratedCompositingActive()) {
-            ASSERT(option == ForceSoftwareRenderingAndIgnoreGPUResidentContent);
-            view->setPaintBehavior(oldPaintBehavior);
-        }
-    }
+#if OS(ANDROID)

[danakj, 2014/05/02 23:12:53]

This OS(ANDROID) stuff is a disaster.

abarth: WDYT of adding another WebWidget::paintCompositedWebViewDeprecated()
method for android that wraps a call to paint() in this setPaintBehaviour stuff,
so it's clear when this is happening and that it's wrong?

+    if (isAcceleratedCompositingActive())
+        view->setPaintBehavior(oldPaintBehavior | PaintBehaviorFlattenCompositingLayers);
+#endif
+
+    PageWidgetDelegate::paint(m_page.get(), pageOverlays(), canvas, rect, isTransparent() ? PageWidgetDelegate::Translucent : PageWidgetDelegate::Opaque);
+
+#if OS(ANDROID)
+    if (isAcceleratedCompositingActive())
+        view->setPaintBehavior(oldPaintBehavior);
+#endif
+
+    double paintEnd = currentTime();
+    double pixelsPerSec = (rect.width * rect.height) / (paintEnd - paintStart);
+    blink::Platform::current()->histogramCustomCounts("Renderer4.SoftwarePaintDurationMS", (paintEnd - paintStart) * 1000, 0, 120, 30);
+    blink::Platform::current()->histogramCustomCounts("Renderer4.SoftwarePaintMegapixPerSecond", pixelsPerSec / 1000000, 10, 210, 30);
 }
 
 bool WebViewImpl::compositeAndReadbackAsync(WebCompositeAndReadbackAsyncCallback* callback)
 {
     if (!isAcceleratedCompositingActive())
         return false;
     m_layerTreeView->compositeAndReadbackAsync(callback);
     return true;
 }
 
@@ skipping 2269 matching lines @@
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return false;
 
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace blink