Ensure that render surface layer list is not dirty/empty before hit testing for touch events

cc/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/layer_tree_host_impl.h"
 
 #include <cmath>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 532 matching lines @@
     m_hostImpl->setViewportSize(layoutViewport, deviceViewport);
     m_hostImpl->setDeviceScaleFactor(deviceScaleFactor);
     EXPECT_EQ(m_hostImpl->rootLayer()->maxScrollOffset(), gfx::Vector2d(25, 25));
 
     deviceScaleFactor = 1;
     m_hostImpl->setViewportSize(layoutViewport, layoutViewport);
     m_hostImpl->setDeviceScaleFactor(deviceScaleFactor);
     EXPECT_EQ(m_hostImpl->rootLayer()->maxScrollOffset(), gfx::Vector2d(75, 75));
 }
 
+TEST_P(LayerTreeHostImplTest, clearRootRenderSurfaceAndHitTestTouchHandlerRegion)
+{
+    setupScrollAndContentsLayers(gfx::Size(100, 100));
+    m_hostImpl->setViewportSize(gfx::Size(50, 50), gfx::Size(50, 50));
+    initializeRendererAndDrawFrame();
+
+    // We should be able to hit test for touch event handlers even if the root layer loses
+    // its render surface after the most recent render.
+    m_hostImpl->rootLayer()->clearRenderSurface();
+    m_hostImpl->setNeedsUpdateDrawProperties();
+
+    EXPECT_EQ(m_hostImpl->haveTouchEventHandlersAt(gfx::Point(0, 0)), false);
+}
+
 TEST_P(LayerTreeHostImplTest, implPinchZoom)
 {
     // This test is specific to the page-scale based pinch zoom.
     if (!m_hostImpl->settings().pageScalePinchZoomEnabled)
         return;
 
     setupScrollAndContentsLayers(gfx::Size(100, 100));
     m_hostImpl->setViewportSize(gfx::Size(50, 50), gfx::Size(50, 50));
     initializeRendererAndDrawFrame();
 
@@ skipping 3835 matching lines @@
     gfx::Rect noDamage = gfx::Rect(m_hostImpl->deviceViewportSize());
     drawFrameAndTestDamage(noDamage);
 }
 
 INSTANTIATE_TEST_CASE_P(LayerTreeHostImplTests,
                         LayerTreeHostImplTest,
                         ::testing::Values(false, true));
 
 }  // namespace
 }  // namespace cc