cc: Layer that have empty bounds should still have their contentsScale applied in their transforms.

cc/layer_tree_host_common.cc

 // Copyright 2011 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 "cc/layer_tree_host_common.h"
 
 #include "cc/layer.h"
 #include "cc/layer_impl.h"
 #include "cc/layer_iterator.h"
 #include "cc/layer_sorter.h"
@@ skipping 513 matching lines @@
     if (layer->fixedToContainerLayer()) {
         // Special case: this layer is a composited fixed-position layer; we need to
         // explicitly compensate for all ancestors' nonzero scrollDeltas to keep this layer
         // fixed correctly.
         combinedTransform = currentScrollCompensationMatrix * combinedTransform;
     }
 
     // The drawTransform that gets computed below is effectively the layer's drawTransform, unless
     // the layer itself creates a renderSurface. In that case, the renderSurface re-parents the transforms.
     WebTransformationMatrix drawTransform = combinedTransform;
-    if (!layer->contentBounds().IsEmpty() && !layer->bounds().IsEmpty()) {
-        // M[draw] = M[parent] * LT * S[layer2content]
-        drawTransform.scaleNonUniform(1.0 / layer->contentsScaleX(),
-                                      1.0 / layer->contentsScaleY());
-    }
+    // M[draw] = M[parent] * LT * S[layer2content]
+    drawTransform.scaleNonUniform(1.0 / layer->contentsScaleX(), 1.0 / layer->contentsScaleY());
 
     // layerScreenSpaceTransform represents the transform between root layer's "screen space" and local content space.
     WebTransformationMatrix layerScreenSpaceTransform = fullHierarchyMatrix;
     if (!layer->preserves3D())
         MathUtil::flattenTransformTo2d(layerScreenSpaceTransform);
     layerScreenSpaceTransform.multiply(drawTransform);
     layer->setScreenSpaceTransform(layerScreenSpaceTransform);
 
     gfx::RectF contentRect(gfx::PointF(), layer->contentBounds());
 
@@ skipping 10 matching lines @@
             return;
 
         if (!layer->renderSurface())
             layer->createRenderSurface();
 
         RenderSurfaceType* renderSurface = layer->renderSurface();
         renderSurface->clearLayerLists();
 
         // The owning layer's draw transform has a scale from content to layer space which we need to undo and
         // replace with a scale from the surface's subtree into layer space.
-        if (!layer->contentBounds().IsEmpty() && !layer->bounds().IsEmpty())
-            drawTransform.scaleNonUniform(layer->contentsScaleX(), layer->contentsScaleY());
+        drawTransform.scaleNonUniform(layer->contentsScaleX(), layer->contentsScaleY());
         drawTransform.scaleNonUniform(1 / renderSurfaceSublayerScale.x(), 1 / renderSurfaceSublayerScale.y());
         renderSurface->setDrawTransform(drawTransform);
 
         // The origin of the new surface is the upper left corner of the layer.
         WebTransformationMatrix layerDrawTransform;
         layerDrawTransform.scaleNonUniform(renderSurfaceSublayerScale.x(), renderSurfaceSublayerScale.y());
-        if (!layer->contentBounds().IsEmpty() && !layer->bounds().IsEmpty())
-            layerDrawTransform.scaleNonUniform(1.0 / layer->contentsScaleX(), 1.0 / layer->contentsScaleY());
+        layerDrawTransform.scaleNonUniform(1.0 / layer->contentsScaleX(), 1.0 / layer->contentsScaleY());
         layer->setDrawTransform(layerDrawTransform);
 
         // Inside the surface's subtree, we scale everything to the owning layer's scale.
         // The sublayer matrix transforms centered layer rects into target
         // surface content space.
         sublayerMatrix.makeIdentity();
         sublayerMatrix.scaleNonUniform(renderSurfaceSublayerScale.x(), renderSurfaceSublayerScale.y());
 
         // The opacity value is moved from the layer to its surface, so that the entire subtree properly inherits opacity.
         renderSurface->setDrawOpacity(drawOpacity);
@@ skipping 151 matching lines @@
         clippedContentRect.set_height(std::min(clippedContentRect.height(), maxTextureSize));
 
         if (clippedContentRect.IsEmpty())
             renderSurface->clearLayerLists();
 
         renderSurface->setContentRect(clippedContentRect);
 
         // The owning layer's screenSpaceTransform has a scale from content to layer space which we need to undo and
         // replace with a scale from the surface's subtree into layer space.
         WebTransformationMatrix screenSpaceTransform = layer->screenSpaceTransform();
-        if (!layer->contentBounds().IsEmpty() && !layer->bounds().IsEmpty())
-            screenSpaceTransform.scaleNonUniform(layer->contentsScaleX(), layer->contentsScaleY());
+        screenSpaceTransform.scaleNonUniform(layer->contentsScaleX(), layer->contentsScaleY());
         screenSpaceTransform.scaleNonUniform(1 / renderSurfaceSublayerScale.x(), 1 / renderSurfaceSublayerScale.y());
         renderSurface->setScreenSpaceTransform(screenSpaceTransform);
 
         if (layer->replicaLayer()) {
             WebTransformationMatrix surfaceOriginToReplicaOriginTransform;
             surfaceOriginToReplicaOriginTransform.scaleNonUniform(renderSurfaceSublayerScale.x(), renderSurfaceSublayerScale.y());
             surfaceOriginToReplicaOriginTransform.translate(layer->replicaLayer()->position().x() + layer->replicaLayer()->anchorPoint().x() * bounds.width(),
                                                             layer->replicaLayer()->position().y() + layer->replicaLayer()->anchorPoint().y() * bounds.height());
             surfaceOriginToReplicaOriginTransform.multiply(layer->replicaLayer()->transform());
             surfaceOriginToReplicaOriginTransform.translate(-layer->replicaLayer()->anchorPoint().x() * bounds.width(), -layer->replicaLayer()->anchorPoint().y() * bounds.height());
@@ skipping 164 matching lines @@
 
         foundLayer = currentLayer;
         break;
     }
 
     // This can potentially return 0, which means the screenSpacePoint did not successfully hit test any layers, not even the root layer.
     return foundLayer;
 }
 
 }  // namespace cc