Implement vertex buffer caching in the tessellated path renderer.

tests/PathTest.cpp

Index: tests/PathTest.cpp
diff --git a/tests/PathTest.cpp b/tests/PathTest.cpp
index 8272692167d5de54ee35f00b759c0389485cb2a6..b0bd66726d4eb719a7361970743c8bc1f3992556 100644
--- a/tests/PathTest.cpp
+++ b/tests/PathTest.cpp
@@ -3715,6 +3715,21 @@ static void test_dump(skiatest::Reporter* reporter) {
                                             "path.lineTo(3, 4);\n");
 }
 
+namespace {
+
+class ChangeListener : public SkPathRef::GenIDChangeListener {
+public:
+    ChangeListener(bool *changed) : fChanged(changed) { *fChanged = false; }
+    virtual ~ChangeListener() {}
+    void onChange() override {
+        *fChanged = true;
+    }
+private:
+    bool* fChanged;
+};
+
+}
+
 class PathTest_Private {
 public:
     static void TestPathTo(skiatest::Reporter* reporter) {
@@ -3734,6 +3749,50 @@ public:
         SkRect reverseExpected = {-4, -4, 8, 8};
         REPORTER_ASSERT(reporter, p.getBounds() == reverseExpected);
     }
+
+    static void TestPathrefListeners(skiatest::Reporter* reporter) {
+        SkPath p;
+
+        bool changed = false;
+        p.moveTo(0, 0);
+
+        // Check that listener is notified on moveTo().
+
+        SkPathPriv::AddGenIDChangeListener(p, SkNEW(ChangeListener(&changed)));
+        REPORTER_ASSERT(reporter, !changed);
+        p.moveTo(10, 0);
+        REPORTER_ASSERT(reporter, changed);
+
+        // Check that listener is notified on lineTo().
+        SkPathPriv::AddGenIDChangeListener(p, SkNEW(ChangeListener(&changed)));
+        REPORTER_ASSERT(reporter, !changed);
+        p.lineTo(20, 0);
+        REPORTER_ASSERT(reporter, changed);
+
+        // Check that listener is notified on reset().
+        SkPathPriv::AddGenIDChangeListener(p, SkNEW(ChangeListener(&changed)));
+        REPORTER_ASSERT(reporter, !changed);
+        p.reset();
+        REPORTER_ASSERT(reporter, changed);
+
+        p.moveTo(0, 0);
+
+        // Check that listener is notified on rewind().
+        SkPathPriv::AddGenIDChangeListener(p, SkNEW(ChangeListener(&changed)));
+        REPORTER_ASSERT(reporter, !changed);
+        p.rewind();
+        REPORTER_ASSERT(reporter, changed);
+
+        // Check that listener is notified when pathref is deleted.
+        {
+            SkPath q;
+            q.moveTo(10, 10);
+            SkPathPriv::AddGenIDChangeListener(q, SkNEW(ChangeListener(&changed)));
+            REPORTER_ASSERT(reporter, !changed);
+        }
+        // q went out of scope.
+        REPORTER_ASSERT(reporter, changed);
+    }
 };
 
 DEF_TEST(Paths, reporter) {
@@ -3880,6 +3939,7 @@ DEF_TEST(Paths, reporter) {
     test_contains(reporter);
     PathTest_Private::TestPathTo(reporter);
     PathRefTest_Private::TestPathRef(reporter);
+    PathTest_Private::TestPathrefListeners(reporter);
     test_dump(reporter);
     test_path_crbug389050(reporter);
     test_path_crbugskia2820(reporter);