Consuming a touch move prevents only the next scroll update.

This implements (In Clank) the touch disposition handling method outlined here:
https://docs.google.com/a/chromium.org/document/d/176xYUC3WbiSl7qd08SBW4NiI4_gO0N4PN6tPAq49-68/edit?pli=1#bookmark=id.wu82d53abe2w

We also modify the way in which Aura handles touch move events to line up with the new way Android handles them. That is, consuming a touch move event prevents the next scroll update event, but does not prevent future scroll update events.

This change will have little impact until https://codereview.chromium.org/166923002/ has landed.

BUG=328503

Review URL: https://codereview.chromium.org/156783006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251533 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 64 insertions, 2 deletions

diff --git a/ui/aura/gestures/gesture_recognizer_unittest.cc b/ui/aura/gestures/gesture_recognizer_unittest.cc
index a3fa4d2..5d17de0 100644
--- a/ui/aura/gestures/gesture_recognizer_unittest.cc
+++ b/ui/aura/gestures/gesture_recognizer_unittest.cc
@@ -4038,5 +4038,62 @@ TEST_F(GestureRecognizerTest, TestExceedingSlopSlowly) {
 
 }
 
+TEST_F(GestureRecognizerTest, ScrollAlternatelyConsumedTest) {
+  scoped_ptr<QueueTouchEventDelegate> delegate(
+      new QueueTouchEventDelegate(dispatcher()));
+  TimedEvents tes;
+  const int kWindowWidth = 3000;
+  const int kWindowHeight = 3000;
+  const int kTouchId = 2;
+  gfx::Rect bounds(0, 0, kWindowWidth, kWindowHeight);
+  scoped_ptr<aura::Window> window(CreateTestWindowWithDelegate(
+      delegate.get(), -1234, bounds, root_window()));
+
+  delegate->Reset();
+
+  int x = 0;
+  int y = 0;
+
+  ui::TouchEvent press1(ui::ET_TOUCH_PRESSED, gfx::Point(x, y),
+                        kTouchId, tes.Now());
+  DispatchEventUsingWindowDispatcher(&press1);
+  delegate->ReceivedAck();
+  EXPECT_FALSE(delegate->scroll_begin());
+  EXPECT_FALSE(delegate->scroll_update());
+  delegate->Reset();
+
+  x += 100;
+  y += 100;
+  ui::TouchEvent move1(ui::ET_TOUCH_MOVED, gfx::Point(x, y),
+                       kTouchId, tes.Now());
+  DispatchEventUsingWindowDispatcher(&move1);
+  delegate->ReceivedAck();
+  EXPECT_TRUE(delegate->scroll_begin());
+  EXPECT_TRUE(delegate->scroll_update());
+  delegate->Reset();
+
+  for (int i = 0; i < 3; ++i) {
+    x += 10;
+    y += 10;
+    ui::TouchEvent move2(
+        ui::ET_TOUCH_MOVED, gfx::Point(x, y), kTouchId, tes.Now());
+    DispatchEventUsingWindowDispatcher(&move2);
+    delegate->ReceivedAck();
+    EXPECT_FALSE(delegate->scroll_begin());
+    EXPECT_TRUE(delegate->scroll_update());
+    delegate->Reset();
+
+    x -= 10;
+    y += 10;
+    ui::TouchEvent move3(
+        ui::ET_TOUCH_MOVED, gfx::Point(x, y), kTouchId, tes.Now());
+    DispatchEventUsingWindowDispatcher(&move3);
+    delegate->ReceivedAckPreventDefaulted();
+    EXPECT_FALSE(delegate->scroll_begin());
+    EXPECT_FALSE(delegate->scroll_update());
+    delegate->Reset();
+  }
+}
+
 }  // namespace test
 }  // namespace aura
diff --git a/ui/events/gestures/gesture_sequence.cc b/ui/events/gestures/gesture_sequence.cc
index 6427c17..719e67d 100644
--- a/ui/events/gestures/gesture_sequence.cc
+++ b/ui/events/gestures/gesture_sequence.cc
@@ -138,9 +138,11 @@ enum EdgeStateSignatureType {
   GST_SCROLL_FIRST_RELEASED =
       G(GS_SCROLL, 0, TS_RELEASED, TSI_ALWAYS),
 
-  // Once scroll has started, process all touch-move events.
   GST_SCROLL_FIRST_MOVED =
-      G(GS_SCROLL, 0, TS_MOVED, TSI_ALWAYS),
+      G(GS_SCROLL, 0, TS_MOVED, TSI_NOT_PROCESSED),
+
+  GST_SCROLL_FIRST_MOVED_HANDLED =
+      G(GS_SCROLL, 0, TS_MOVED, TSI_PROCESSED),
 
   GST_SCROLL_FIRST_CANCELLED =
       G(GS_SCROLL, 0, TS_CANCELLED, TSI_ALWAYS),
@@ -352,6 +354,7 @@ EdgeStateSignatureType Signature(GestureState gesture_state,
     case GST_SYNTHETIC_CLICK_ABORTED_SECOND_PRESSED:
     case GST_SCROLL_FIRST_RELEASED:
     case GST_SCROLL_FIRST_MOVED:
+    case GST_SCROLL_FIRST_MOVED_HANDLED:
     case GST_SCROLL_FIRST_CANCELLED:
     case GST_SCROLL_SECOND_PRESSED:
     case GST_PENDING_TWO_FINGER_TAP_FIRST_RELEASED:
@@ -608,6 +611,8 @@ GestureSequence::Gestures* GestureSequence::ProcessTouchEventForGesture(
       if (ScrollUpdate(event, point, gestures.get(), FS_NOT_FIRST_SCROLL))
         point.UpdateForScroll();
       break;
+    case GST_SCROLL_FIRST_MOVED_HANDLED:
+      break;
     case GST_SCROLL_FIRST_RELEASED:
     case GST_SCROLL_FIRST_CANCELLED:
       ScrollEnd(event, point, gestures.get());