Decouple EventWithLatencyInfo and WebInputEventTraits [extern templates]

content/common/input/web_input_event_traits.cc

Index: content/common/input/web_input_event_traits.cc
diff --git a/content/common/input/web_input_event_traits.cc b/content/common/input/web_input_event_traits.cc
index fd2115021fc221b56a99b8debe16430f74c17b04..9ec16179569c01d54ff7f00bd63d4924681c11cb 100644
--- a/content/common/input/web_input_event_traits.cc
+++ b/content/common/input/web_input_event_traits.cc
@@ -4,9 +4,6 @@
 
 #include "content/common/input/web_input_event_traits.h"
 
-#include <bitset>
-#include <limits>
-
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 
@@ -19,13 +16,10 @@ using blink::WebMouseEvent;
 using blink::WebMouseWheelEvent;
 using blink::WebTouchEvent;
 using blink::WebTouchPoint;
-using std::numeric_limits;
 
 namespace content {
 namespace {
 
-const int kInvalidTouchIndex = -1;
-
 void ApppendEventDetails(const WebKeyboardEvent& event, std::string* result) {
   StringAppendF(result,
                 "{\n WinCode: %d\n NativeCode: %d\n IsSystem: %d\n"
@@ -112,189 +106,6 @@ void ApppendEventDetails(const WebTouchEvent& event, std::string* result) {
   result->append(" ]\n}");
 }
 
-bool CanCoalesce(const WebKeyboardEvent& event_to_coalesce,
-                 const WebKeyboardEvent& event) {
-  return false;
-}
-
-void Coalesce(const WebKeyboardEvent& event_to_coalesce,
-              WebKeyboardEvent* event) {
-  DCHECK(CanCoalesce(event_to_coalesce, *event));
-}
-
-bool CanCoalesce(const WebMouseEvent& event_to_coalesce,
-                 const WebMouseEvent& event) {
-  return event.type == event_to_coalesce.type &&
-         event.type == WebInputEvent::MouseMove;
-}
-
-void Coalesce(const WebMouseEvent& event_to_coalesce, WebMouseEvent* event) {
-  DCHECK(CanCoalesce(event_to_coalesce, *event));
-  // Accumulate movement deltas.
-  int x = event->movementX;
-  int y = event->movementY;
-  *event = event_to_coalesce;
-  event->movementX += x;
-  event->movementY += y;
-}
-
-bool CanCoalesce(const WebMouseWheelEvent& event_to_coalesce,
-                 const WebMouseWheelEvent& event) {
-  return event.modifiers == event_to_coalesce.modifiers &&
-         event.scrollByPage == event_to_coalesce.scrollByPage &&
-         event.phase == event_to_coalesce.phase &&
-         event.momentumPhase == event_to_coalesce.momentumPhase &&
-         event.hasPreciseScrollingDeltas ==
-             event_to_coalesce.hasPreciseScrollingDeltas;
-}
-
-float GetUnacceleratedDelta(float accelerated_delta, float acceleration_ratio) {
-  return accelerated_delta * acceleration_ratio;
-}
-
-float GetAccelerationRatio(float accelerated_delta, float unaccelerated_delta) {
-  if (unaccelerated_delta == 0.f || accelerated_delta == 0.f)
-    return 1.f;
-  return unaccelerated_delta / accelerated_delta;
-}
-
-void Coalesce(const WebMouseWheelEvent& event_to_coalesce,
-              WebMouseWheelEvent* event) {
-  DCHECK(CanCoalesce(event_to_coalesce, *event));
-  float unaccelerated_x =
-      GetUnacceleratedDelta(event->deltaX,
-                            event->accelerationRatioX) +
-      GetUnacceleratedDelta(event_to_coalesce.deltaX,
-                            event_to_coalesce.accelerationRatioX);
-  float unaccelerated_y =
-      GetUnacceleratedDelta(event->deltaY,
-                            event->accelerationRatioY) +
-      GetUnacceleratedDelta(event_to_coalesce.deltaY,
-                            event_to_coalesce.accelerationRatioY);
-  event->deltaX += event_to_coalesce.deltaX;
-  event->deltaY += event_to_coalesce.deltaY;
-  event->wheelTicksX += event_to_coalesce.wheelTicksX;
-  event->wheelTicksY += event_to_coalesce.wheelTicksY;
-  event->accelerationRatioX =
-      GetAccelerationRatio(event->deltaX, unaccelerated_x);
-  event->accelerationRatioY =
-      GetAccelerationRatio(event->deltaY, unaccelerated_y);
-}
-
-// Returns |kInvalidTouchIndex| iff |event| lacks a touch with an ID of |id|.
-int GetIndexOfTouchID(const WebTouchEvent& event, int id) {
-  for (unsigned i = 0; i < event.touchesLength; ++i) {
-    if (event.touches[i].id == id)
-      return i;
-  }
-  return kInvalidTouchIndex;
-}
-
-WebInputEvent::DispatchType MergeDispatchTypes(
-    WebInputEvent::DispatchType type_1,
-    WebInputEvent::DispatchType type_2) {
-  static_assert(WebInputEvent::DispatchType::Blocking <
-                    WebInputEvent::DispatchType::EventNonBlocking,
-                "Enum not ordered correctly");
-  static_assert(WebInputEvent::DispatchType::EventNonBlocking <
-                    WebInputEvent::DispatchType::ListenersNonBlockingPassive,
-                "Enum not ordered correctly");
-  static_assert(
-      WebInputEvent::DispatchType::ListenersNonBlockingPassive <
-          WebInputEvent::DispatchType::ListenersForcedNonBlockingPassive,
-      "Enum not ordered correctly");
-  return static_cast<WebInputEvent::DispatchType>(
-      std::min(static_cast<int>(type_1), static_cast<int>(type_2)));
-}
-
-bool CanCoalesce(const WebTouchEvent& event_to_coalesce,
-                 const WebTouchEvent& event) {
-  if (event.type != event_to_coalesce.type ||
-      event.type != WebInputEvent::TouchMove ||
-      event.modifiers != event_to_coalesce.modifiers ||
-      event.touchesLength != event_to_coalesce.touchesLength ||
-      event.touchesLength > WebTouchEvent::touchesLengthCap)
-    return false;
-
-  static_assert(WebTouchEvent::touchesLengthCap <= sizeof(int32_t) * 8U,
-                "suboptimal touchesLengthCap size");
-  // Ensure that we have a 1-to-1 mapping of pointer ids between touches.
-  std::bitset<WebTouchEvent::touchesLengthCap> unmatched_event_touches(
-      (1 << event.touchesLength) - 1);
-  for (unsigned i = 0; i < event_to_coalesce.touchesLength; ++i) {
-    int event_touch_index =
-        GetIndexOfTouchID(event, event_to_coalesce.touches[i].id);
-    if (event_touch_index == kInvalidTouchIndex)
-      return false;
-    if (!unmatched_event_touches[event_touch_index])
-      return false;
-    unmatched_event_touches[event_touch_index] = false;
-  }
-  return unmatched_event_touches.none();
-}
-
-void Coalesce(const WebTouchEvent& event_to_coalesce, WebTouchEvent* event) {
-  DCHECK(CanCoalesce(event_to_coalesce, *event));
-  // The WebTouchPoints include absolute position information. So it is
-  // sufficient to simply replace the previous event with the new event->
-  // However, it is necessary to make sure that all the points have the
-  // correct state, i.e. the touch-points that moved in the last event, but
-  // didn't change in the current event, will have Stationary state. It is
-  // necessary to change them back to Moved state.
-  WebTouchEvent old_event = *event;
-  *event = event_to_coalesce;
-  for (unsigned i = 0; i < event->touchesLength; ++i) {
-    int i_old = GetIndexOfTouchID(old_event, event->touches[i].id);
-    if (old_event.touches[i_old].state == blink::WebTouchPoint::StateMoved)
-      event->touches[i].state = blink::WebTouchPoint::StateMoved;
-  }
-  event->movedBeyondSlopRegion |= old_event.movedBeyondSlopRegion;
-  event->dispatchType = MergeDispatchTypes(old_event.dispatchType,
-                                           event_to_coalesce.dispatchType);
-}
-
-bool CanCoalesce(const WebGestureEvent& event_to_coalesce,
-                 const WebGestureEvent& event) {
-  if (event.type != event_to_coalesce.type ||
-      event.sourceDevice != event_to_coalesce.sourceDevice ||
-      event.modifiers != event_to_coalesce.modifiers)
-    return false;
-
-  if (event.type == WebInputEvent::GestureScrollUpdate)
-    return true;
-
-  // GesturePinchUpdate scales can be combined only if they share a focal point,
-  // e.g., with double-tap drag zoom.
-  if (event.type == WebInputEvent::GesturePinchUpdate &&
-      event.x == event_to_coalesce.x &&
-      event.y == event_to_coalesce.y)
-    return true;
-
-  return false;
-}
-
-void Coalesce(const WebGestureEvent& event_to_coalesce,
-              WebGestureEvent* event) {
-  DCHECK(CanCoalesce(event_to_coalesce, *event));
-  if (event->type == WebInputEvent::GestureScrollUpdate) {
-    event->data.scrollUpdate.deltaX +=
-        event_to_coalesce.data.scrollUpdate.deltaX;
-    event->data.scrollUpdate.deltaY +=
-        event_to_coalesce.data.scrollUpdate.deltaY;
-    DCHECK_EQ(
-        event->data.scrollUpdate.previousUpdateInSequencePrevented,
-        event_to_coalesce.data.scrollUpdate.previousUpdateInSequencePrevented);
-  } else if (event->type == WebInputEvent::GesturePinchUpdate) {
-    event->data.pinchUpdate.scale *= event_to_coalesce.data.pinchUpdate.scale;
-    // Ensure the scale remains bounded above 0 and below Infinity so that
-    // we can reliably perform operations like log on the values.
-    if (event->data.pinchUpdate.scale < numeric_limits<float>::min())
-      event->data.pinchUpdate.scale = numeric_limits<float>::min();
-    else if (event->data.pinchUpdate.scale > numeric_limits<float>::max())
-      event->data.pinchUpdate.scale = numeric_limits<float>::max();
-  }
-}
-
 struct WebInputEventToString {
   template <class EventType>
   bool Execute(const WebInputEvent& event, std::string* result) const {
@@ -338,33 +149,6 @@ struct WebInputEventDelete {
   }
 };
 
-struct WebInputEventCanCoalesce {
-  template <class EventType>
-  bool Execute(const WebInputEvent& event_to_coalesce,
-               const WebInputEvent* event) const {
-    if (event_to_coalesce.type != event->type)
-      return false;
-    DCHECK_EQ(sizeof(EventType), event->size);
-    DCHECK_EQ(sizeof(EventType), event_to_coalesce.size);
-    return CanCoalesce(static_cast<const EventType&>(event_to_coalesce),
-                       *static_cast<const EventType*>(event));
-  }
-};
-
-struct WebInputEventCoalesce {
-  template <class EventType>
-  bool Execute(const WebInputEvent& event_to_coalesce,
-               WebInputEvent* event) const {
-    // New events get coalesced into older events, and the newer timestamp
-    // should always be preserved.
-    const double time_stamp_seconds = event_to_coalesce.timeStampSeconds;
-    Coalesce(static_cast<const EventType&>(event_to_coalesce),
-             static_cast<EventType*>(event));
-    event->timeStampSeconds = time_stamp_seconds;
-    return true;
-  }
-};
-
 template <typename Operator, typename ArgIn, typename ArgOut>
 bool Apply(Operator op,
            WebInputEvent::Type type,
@@ -460,23 +244,6 @@ void WebInputEventTraits::Delete(WebInputEvent* event) {
   Apply(WebInputEventDelete(), event->type, event, &dummy_var);
 }
 
-bool WebInputEventTraits::CanCoalesce(const WebInputEvent& event_to_coalesce,
-                                      const WebInputEvent& event) {
-  // Early out before casting.
-  if (event_to_coalesce.type != event.type)
-    return false;
-  return Apply(WebInputEventCanCoalesce(),
-               event.type,
-               event_to_coalesce,
-               &event);
-}
-
-void WebInputEventTraits::Coalesce(const WebInputEvent& event_to_coalesce,
-                                   WebInputEvent* event) {
-  DCHECK(event);
-  Apply(WebInputEventCoalesce(), event->type, event_to_coalesce, event);
-}
-
 bool WebInputEventTraits::ShouldBlockEventStream(const WebInputEvent& event) {
   switch (event.type) {
     case WebInputEvent::MouseDown: