Implement on demand quad rasterization for PicturePiles.

cc/trees/layer_tree_host_impl_unittest.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/trees/layer_tree_host_impl.h"
 
 #include <cmath>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 2623 matching lines @@
     scoped_ptr<IOSurfaceLayerImpl> ioSurfaceLayer = IOSurfaceLayerImpl::Create(m_hostImpl->active_tree(), 5);
     ioSurfaceLayer->SetBounds(gfx::Size(10, 10));
     ioSurfaceLayer->SetAnchorPoint(gfx::PointF(0, 0));
     ioSurfaceLayer->SetContentBounds(gfx::Size(10, 10));
     ioSurfaceLayer->SetDrawsContent(true);
     ioSurfaceLayer->SetIOSurfaceProperties(1, gfx::Size(10, 10));
     rootLayer->AddChild(ioSurfaceLayer.PassAs<LayerImpl>());
 
     m_hostImpl->active_tree()->SetRootLayer(rootLayer.Pass());
 
-    EXPECT_EQ(0u, context3d->NumTextures());
+    // An auxiliary texture is created for on-demand rasterization.
+    EXPECT_EQ(1u, context3d->NumTextures());
 
     LayerTreeHostImpl::FrameData frame;
     EXPECT_TRUE(m_hostImpl->PrepareToDraw(&frame));
     m_hostImpl->DrawLayers(&frame, base::TimeTicks::Now());
     m_hostImpl->DidDrawAllLayers(frame);
     m_hostImpl->SwapBuffers();
 
-    EXPECT_GT(context3d->NumTextures(), 0u);
+    EXPECT_GT(context3d->NumTextures(), 1u);
 
     // Kill the layer tree.
     m_hostImpl->active_tree()->SetRootLayer(LayerImpl::Create(m_hostImpl->active_tree(), 100));
     // There should be no textures left in use after.
-    EXPECT_EQ(0u, context3d->NumTextures());
+    EXPECT_EQ(1u, context3d->NumTextures());
 }
 
 class MockDrawQuadsToFillScreenContext : public TestWebGraphicsContext3D {
 public:
     MOCK_METHOD1(useProgram, void(WebKit::WebGLId program));
     MOCK_METHOD4(drawElements, void(WebKit::WGC3Denum mode, WebKit::WGC3Dsizei count, WebKit::WGC3Denum type, WebKit::WGC3Dintptr offset));
 };
 
 TEST_F(LayerTreeHostImplTest, hasTransparentBackground)
 {
@@ skipping 1674 matching lines @@
         EXPECT_EQ(gfx::Rect(0, 0, 100, 100).ToString(), renderPassQuad->rect.ToString());
         EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(), renderPassQuad->mask_uv_rect.ToString());
 
         m_hostImpl->DrawLayers(&frame, base::TimeTicks::Now());
         m_hostImpl->DidDrawAllLayers(frame);
     }
 }
 
 }  // namespace
 }  // namespace cc