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 313d84a142bc9c84a029c8968df0ef64d693b408..0453bdd9f70cda0f319e3810e8012afd31d45bdd 100644
--- a/tests/PathTest.cpp
+++ b/tests/PathTest.cpp
@@ -3699,6 +3699,64 @@ public:
     }
 };
 
+namespace {
+
+class ChangeListener : public SkPathRef::GenIDChangeListener {
+public:
+    ChangeListener(bool *changed) : fChanged(changed) { *fChanged = false; }
+    virtual ~ChangeListener() {}
+    void onChange() override {
+        *fChanged = true;
+    }
+private:
+    bool* fChanged;
+};
+
+}
+
+static void test_pathref_listeners(skiatest::Reporter* reporter) {
+    SkPath p;
+
+    bool changed = false;
+    p.moveTo(0, 0);
+
+    // Check that listener is notified on moveTo().
+    p.pathRef()->addGenIDChangeListener(SkNEW(ChangeListener(&changed)));
+    REPORTER_ASSERT(reporter, !changed);
+    p.moveTo(10, 0);
+    REPORTER_ASSERT(reporter, changed);
+
+    // Check that listener is notified on lineTo().
+    p.pathRef()->addGenIDChangeListener(SkNEW(ChangeListener(&changed)));
+    REPORTER_ASSERT(reporter, !changed);
+    p.lineTo(20, 0);
+    REPORTER_ASSERT(reporter, changed);
+
+    // Check that listener is notified on reset().
+    p.pathRef()->addGenIDChangeListener(SkNEW(ChangeListener(&changed)));
+    REPORTER_ASSERT(reporter, !changed);
+    p.reset();
+    REPORTER_ASSERT(reporter, changed);
+
+    p.moveTo(0, 0);
+
+    // Check that listener is notified on rewind().
+    p.pathRef()->addGenIDChangeListener(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);
+        q.pathRef()->addGenIDChangeListener(SkNEW(ChangeListener(&changed)));
+        REPORTER_ASSERT(reporter, !changed);
+    }
+    // q went out of scope.
+    REPORTER_ASSERT(reporter, changed);
+}
+
 DEF_TEST(Paths, reporter) {
     test_path_crbug364224();
 
@@ -3848,4 +3906,5 @@ DEF_TEST(Paths, reporter) {
     test_path_crbugskia2820(reporter);
     test_skbug_3469(reporter);
     test_skbug_3239(reporter);
+    test_pathref_listeners(reporter);
 }