Use non-empty size in CompositingSimTest setup

Painting will early-out unless a non-empty frame size is used. This
patch makes the CompositingSimTest setup set a frame size. This issue
sunk several hours when writing https://crrev.com/732194.

Bug: 1014273
Change-Id: Id1d95daa8c96397bdccc36b0bc498a1ba8a24ac5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2003556
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Auto-Submit: Philip Rogers <pdr@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732429}

third_party/blink/renderer/core/paint/compositing/compositing_test.cc

@@ -213,8 +213,6 @@ TEST_P(CompositingTest, WillChangeTransformHint) {
 class CompositingSimTest : public PaintTestConfigurations, public SimTest {
  public:
   void InitializeWithHTML(const String& html) {
-    WebView().MainFrameWidget()->Resize(WebSize(800, 600));
-
     SimRequest request("https://example.com/test.html", "text/html");
     LoadURL("https://example.com/test.html");
     request.Complete(html);
@@ -262,6 +260,13 @@ class CompositingSimTest : public PaintTestConfigurations, public SimTest {
   PaintArtifactCompositor* paint_artifact_compositor() {
     return MainFrame().GetFrameView()->GetPaintArtifactCompositor();
   }
+
+ private:
+  void SetUp() override {
+    SimTest::SetUp();
+    // Ensure a non-empty size so painting does not early-out.
+    WebView().Resize(WebSize(800, 600));
+  }
 };
 
 INSTANTIATE_PAINT_TEST_SUITE_P(CompositingSimTest);
@@ -1075,7 +1080,6 @@ TEST_P(CompositingSimTest, PromoteCrossOriginIframeAfterLoading) {
   feature_list.InitWithFeatureState(
       blink::features::kCompositeCrossOriginIframes, true);
 
-  WebView().MainFrameWidget()->Resize(WebSize(800, 600));
   SimRequest main_resource("https://origin-a.com/a.html", "text/html");
   SimRequest frame_resource("https://origin-b.com/b.html", "text/html");
 
@@ -1097,7 +1101,6 @@ TEST_P(CompositingSimTest, PromoteCrossOriginIframeAfterDomainChange) {
   feature_list.InitWithFeatureState(
       blink::features::kCompositeCrossOriginIframes, true);
 
-  WebView().MainFrameWidget()->Resize(WebSize(800, 600));
   SimRequest main_resource("https://origin-a.com/a.html", "text/html");
   SimRequest frame_resource("https://sub.origin-a.com/b.html", "text/html");