Remove root layer specialness in calculateDrawTransforms

cc/test/layer_test_common.cc

 // Copyright 2012 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 "config.h"
 
 #include "cc/test/layer_test_common.h"
 
 #include "cc/draw_quad.h"
+#include "cc/math_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace LayerTestCommon {
 
 // Align with expected and actual output
 const char* quadString = "    Quad: ";
 
+bool floatRectCanBeSafelyRoundedToIntRect(const cc::FloatRect& r)
+{
+    // Ensure that range of float values is not beyond integer range.
+    if (!r.isExpressibleAsIntRect())
+        return false;
+
+    // Ensure that the values are actually integers.
+    if (floorf(r.x()) == r.x()
+        && floorf(r.y()) == r.y()
+        && floorf(r.width()) == r.width()
+        && floorf(r.height()) == r.height())
+        return true;
+
+    return false;
+}
+
 void verifyQuadsExactlyCoverRect(const cc::QuadList& quads,
                                  const cc::IntRect& rect) {
     cc::Region remaining(rect);
 
     for (size_t i = 0; i < quads.size(); ++i) {
         cc::DrawQuad* quad = quads[i];
-        cc::IntRect quadRect = cc::IntRect(quad->quadRect());
+        cc::FloatRect floatQuadRect = cc::MathUtil::mapClippedRect(quad->sharedQuadState()->quadTransform, cc::FloatRect(quad->quadRect()));
+
+        // Before testing for exact coverage in the integer world, assert that rounding
+        // will not round the rect incorrectly.
+        ASSERT_TRUE(floatRectCanBeSafelyRoundedToIntRect(floatQuadRect));
+
+        cc::IntRect quadRect = enclosingIntRect(floatQuadRect);
 
         EXPECT_TRUE(rect.contains(quadRect)) << quadString << i;
         EXPECT_TRUE(remaining.contains(quadRect)) << quadString << i;
         remaining.subtract(cc::Region(quadRect));
     }
 
     EXPECT_TRUE(remaining.isEmpty());
 }
 
 }  // namespace LayerTestCommon