Only allow subsequence caching for SVG documents, not inline SVG.

third_party/WebKit/Source/core/svg/graphics/SVGImageTest.cpp

 // Copyright 2016 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 "core/svg/graphics/SVGImage.h"
 
+#include "core/frame/FrameView.h"
+#include "core/layout/LayoutView.h"
+#include "core/paint/PaintLayer.h"
 #include "core/svg/graphics/SVGImageChromeClient.h"
 #include "platform/SharedBuffer.h"
 #include "platform/Timer.h"
 #include "platform/geometry/FloatRect.h"
 #include "platform/graphics/paint/PaintCanvas.h"
 #include "platform/graphics/paint/PaintFlags.h"
 #include "platform/testing/UnitTestHelpers.h"
 #include "platform/wtf/PtrUtil.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkCanvas.h"
@@ skipping 121 matching lines @@
   testing::RunDelayedTasks(1.0 + timer->NextFireInterval() * 1000.0);
   EXPECT_TRUE(chrome_client.IsSuspended());
   EXPECT_FALSE(timer->IsActive());
 
   // Simulate a draw. This should resume the animation again.
   PumpFrame();
   EXPECT_FALSE(chrome_client.IsSuspended());
   EXPECT_TRUE(timer->IsActive());
 }
 
+TEST_F(SVGImageTest, SupportsSubsequenceCaching) {
+  const bool kShouldPause = true;
+  Load(kAnimatedDocument, kShouldPause);
+  PumpFrame();
+  LocalFrame* local_frame = ToLocalFrame(GetImage().GetPage()->MainFrame());
+  EXPECT_TRUE(local_frame->GetDocument()->IsSVGDocument());
+  LayoutObject* svg_root = local_frame->View()->GetLayoutView()->ChildAt(0);

[fs, 2017/05/17 11:14:45]

Nit: s/ChildAt(0)/FirstChild/ (ChildAt is quite the oddity, and we should
probably avoid adding new uses of it... even more so when they are this trivial)

[chrishtr, 2017/05/17 17:01:18]

Done.

+  EXPECT_TRUE(svg_root->IsSVGRoot());
+  EXPECT_TRUE(
+      ToLayoutBoxModelObject(svg_root)->Layer()->SupportsSubsequenceCaching());
+}
+
 }  // namespace blink