cc: Make full-pile invalidations cheap.

cc/resources/picture_pile_unittest.cc

Index: cc/resources/picture_pile_unittest.cc
diff --git a/cc/resources/picture_pile_unittest.cc b/cc/resources/picture_pile_unittest.cc
index 15cb3d31e3e7fc48630c6e3c673713bcecc8b21d..d58a8bc398656cd3181dcbc70e2e8949db9a231d 100644
--- a/cc/resources/picture_pile_unittest.cc
+++ b/cc/resources/picture_pile_unittest.cc
@@ -364,6 +364,66 @@ TEST_F(PicturePileTest, NoInvalidationValidViewport) {
   EXPECT_EQ(Region().ToString(), invalidation.ToString());
 }
 
+TEST_F(PicturePileTest, BigFullLayerInvalidation) {
+  gfx::Size huge_layer_size(100000000, 100000000);
+  gfx::Rect viewport(300000, 400000, 5000, 6000);
+
+  // Resize the pile.
+  Region invalidation;
+  UpdateAndExpandInvalidation(&invalidation, huge_layer_size, viewport);
+
+  // Invalidating a huge layer should be fast.
+  base::TimeTicks start = base::TimeTicks::Now();
+  invalidation = gfx::Rect(huge_layer_size);
+  UpdateAndExpandInvalidation(&invalidation, huge_layer_size, viewport);
+  base::TimeTicks end = base::TimeTicks::Now();
+  base::TimeDelta length = end - start;
+  // This is verrrry generous to avoid flake.
+  EXPECT_LT(length.InSeconds(), 5);
+}
+
+TEST_F(PicturePileTest, BigFullLayerInvalidationWithResizeGrow) {
+  gfx::Size huge_layer_size(100000000, 100000000);
+  gfx::Rect viewport(300000, 400000, 5000, 6000);
+
+  // Resize the pile.
+  Region invalidation;
+  UpdateAndExpandInvalidation(&invalidation, huge_layer_size, viewport);
+
+  // Resize the pile even larger, while invalidating everything in the old size.
+  // Invalidating the whole thing should be fast.
+  base::TimeTicks start = base::TimeTicks::Now();
+  gfx::Size bigger_layer_size(huge_layer_size.width() * 2,
+                              huge_layer_size.height() * 2);
+  invalidation = gfx::Rect(huge_layer_size);
+  UpdateAndExpandInvalidation(&invalidation, bigger_layer_size, viewport);
+  base::TimeTicks end = base::TimeTicks::Now();
+  base::TimeDelta length = end - start;
+  // This is verrrry generous to avoid flake.
+  EXPECT_LT(length.InSeconds(), 5);
+}
+
+TEST_F(PicturePileTest, BigFullLayerInvalidationWithResizeShrink) {
+  gfx::Size huge_layer_size(100000000, 100000000);
+  gfx::Rect viewport(300000, 400000, 5000, 6000);
+
+  // Resize the pile.
+  Region invalidation;
+  UpdateAndExpandInvalidation(&invalidation, huge_layer_size, viewport);
+
+  // Resize the pile smaller, while invalidating everything in the new size.
+  // Invalidating the whole thing should be fast.
+  base::TimeTicks start = base::TimeTicks::Now();
+  gfx::Size smaller_layer_size(huge_layer_size.width() - 1000,
+                               huge_layer_size.height() - 1000);
+  invalidation = gfx::Rect(smaller_layer_size);
+  UpdateAndExpandInvalidation(&invalidation, smaller_layer_size, viewport);
+  base::TimeTicks end = base::TimeTicks::Now();
+  base::TimeDelta length = end - start;
+  // This is verrrry generous to avoid flake.
+  EXPECT_LT(length.InSeconds(), 5);

[enne (OOO), 2014/10/11 00:26:33]

Are there correctness tests you can do here too, like making sure recordings are
rerecorded, or the grid cells in PicturePile are invalidated?  That's my biggest
worry--that any optimization for invalidating everything does something
incorrectly.

I have to admit I'm not super keen on the "this test passes if it doesn't take
that long" strategy.  It's like a performance test baked into a unit test.  I'd
almost just say don't test the speed at all if you have local measurements that
support what you're doing.  Maybe other folks feel differently.

[danakj, 2014/10/11 00:30:22]

Hmm ya I guess that'd be good. I did break some LTH tests when I had a copy in
that loop so that's something, but making sure it even does something would be
good.
OTOH there are a bunch of cases here, and I totally missed this last one at
first (it's the || in the if statement). It'd be easy to miss it again in a
refactor.

+}
+
 TEST_F(PicturePileTest, InvalidationOutsideRecordingRect) {
   gfx::Size huge_layer_size(10000000, 20000000);
   gfx::Rect viewport(300000, 400000, 5000, 6000);