Optimize repaint on FrameView resize

Source/web/tests/WebFrameTest.cpp

Index: Source/web/tests/WebFrameTest.cpp
diff --git a/Source/web/tests/WebFrameTest.cpp b/Source/web/tests/WebFrameTest.cpp
index 9645e9a27015c80799f8db0fa0eee32abe8e5e3f..dc9318a272a0bf95b75fe1f7dfc8d2c6f772a8e7 100644
--- a/Source/web/tests/WebFrameTest.cpp
+++ b/Source/web/tests/WebFrameTest.cpp
@@ -5283,6 +5283,79 @@ TEST_F(WebFrameTest, CreateChildFrameFailure)
     EXPECT_EQ(1, client.callCount());
 }
 
+TEST_F(WebFrameTest, sizeChangeRepaint)
+{
+    const char* kTests[] = {
+        "repaint/size-change-repaint1.html",
+        "repaint/size-change-repaint2.html",
+        "repaint/size-change-repaint3.html",
+        "repaint/size-change-repaint4.html",
+        "repaint/size-change-repaint5.html",
+        "repaint/size-change-repaint6.html",
+        "repaint/size-change-repaint7.html",
+        "repaint/size-change-repaint8.html",
+        "repaint/size-change-repaint9.html",
+        "repaint/size-change-repaint10.html",
+    };
+
+    const WebCore::IntRect kExpectedRepaintOnHeightChange[] = {
+        WebCore::IntRect(0, 200, 200, 100),
+        WebCore::IntRect(0, 200, 200, 100),
+        WebCore::IntRect(0, 200, 200, 100),
+        WebCore::IntRect(0, 0, 200, 300),
+        WebCore::IntRect(0, 0, 200, 300),
+        WebCore::IntRect(0, 0, 200, 300),
+        WebCore::IntRect(0, 100, 200, 200),
+        WebCore::IntRect(0, 100, 200, 200),
+        WebCore::IntRect(0, 160, 200, 140),
+        WebCore::IntRect(0, 50, 200, 250),
+    };
+
+    const WebCore::IntRect kExpectedRepaintOnWidthChange[] = {
+        WebCore::IntRect(0, 0, 300, 300),
+        WebCore::IntRect(0, 0, 300, 300),
+        WebCore::IntRect(0, 0, 300, 300),
+        WebCore::IntRect(0, 0, 300, 300),
+        WebCore::IntRect(0, 0, 300, 300),
+        WebCore::IntRect(0, 0, 300, 300),
+        WebCore::IntRect(0, 0, 300, 300),
+        WebCore::IntRect(0, 0, 300, 300),
+        WebCore::IntRect(0, 0, 300, 300),
+        WebCore::IntRect(0, 0, 300, 300),
+    };
+
+    UseMockScrollbarSettings mockScrollbarSettings;
+
+    FrameTestHelpers::WebViewHelper webViewHelper;
+    WebViewImpl* webView = webViewHelper.initialize(true);
+
+    for (size_t i = 0; i < arraysize(kTests); ++i) {
+        SCOPED_TRACE(kTests[i]);
+        registerMockedHttpURLLoad(kTests[i]);
+        FrameTestHelpers::loadFrame(webView->mainFrame(), m_baseURL + kTests[i]);
+        Platform::current()->unitTestSupport()->serveAsynchronousMockedRequests();
+
+        webView->resize(WebSize(200, 200));
+        webView->layout();
+
+        // Change height.
+        WebCore::FrameView* frameView = webView->mainFrameImpl()->frameView();
+        frameView->setTracksRepaints(true);
+        webView->resize(WebSize(200, 300));
+        webView->layout();
+        WebCore::IntRect repaintRect = WebCore::intersection(WebCore::IntRect(0, 0, 200, 300), WebCore::unionRect(frameView->trackedRepaintRects()));
+        EXPECT_EQ_RECT(kExpectedRepaintOnHeightChange[i], repaintRect);
+
+        // Change width.
+        frameView->setTracksRepaints(true);
+        webView->resize(WebSize(300, 300));
+        webView->layout();
+        repaintRect = WebCore::intersection(WebCore::IntRect(0, 0, 300, 300), WebCore::unionRect(frameView->trackedRepaintRects()));
+        EXPECT_EQ_RECT(kExpectedRepaintOnWidthChange[i], repaintRect);
+        frameView->setTracksRepaints(false);
+    }
+}
+
 TEST_F(WebFrameTest, fixedPositionInFixedViewport)
 {
     UseMockScrollbarSettings mockScrollbarSettings;