[Android] Perform eager gesture recognition on MotionEvents

content/browser/android/content_view_core_impl.cc

Index: content/browser/android/content_view_core_impl.cc
diff --git a/content/browser/android/content_view_core_impl.cc b/content/browser/android/content_view_core_impl.cc
index 00b3442010290dafd518dcdc525b0d1ad4100529..64cd6edee5b496af45c82289d06d73158e951489 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -110,6 +110,31 @@ ScopedJavaLocalRef<jobject> CreateJavaRect(
                                       static_cast<int>(rect.bottom())));
 }
 
+bool PossiblyTriggeredByTimeout(const WebGestureEvent& event) {
+  switch (event.type) {
+    case WebInputEvent::GestureShowPress:
+    case WebInputEvent::GestureLongPress:
+      return true;
+    // On Android, a GestureTap may be sent after a certain timeout window
+    // if there is no GestureDoubleTap follow-up.
+    case WebInputEvent::GestureTap:
+      return true;
+    // On Android, a GestureTapCancel may be triggered by the loss of window
+    //  focus (e.g., following a GestureLongPress).
+    case WebInputEvent::GestureTapCancel:
+      return true;
+    default:
+      break;
+  }
+  return false;
+}
+
+GestureEventPacket::GestureSource
+ToGestureSource(const WebGestureEvent& event) {
+  return PossiblyTriggeredByTimeout(event) ? GestureEventPacket::TOUCH_TIMEOUT
+                                           : GestureEventPacket::SYNTHETIC;
+}
+
 }  // namespace
 
 // Enables a callback when the underlying WebContents is destroyed, to enable
@@ -176,7 +201,9 @@ ContentViewCoreImpl::ContentViewCoreImpl(JNIEnv* env, jobject obj,
       view_android_(view_android),
       window_android_(window_android),
       device_orientation_(0),
-      geolocation_needs_pause_(false) {
+      geolocation_needs_pause_(false),
+      gesture_event_queue_(this),
+      handling_touch_event_(false) {
   CHECK(web_contents) <<
       "A ContentViewCoreImpl should be created with a valid WebContents.";
 
@@ -304,6 +331,22 @@ void ContentViewCoreImpl::RenderViewReady() {
     SendOrientationChangeEventInternal();
 }
 
+void ContentViewCoreImpl::ForwardGestureEvent(
+    const blink::WebGestureEvent& event) {
+  JNIEnv* env = AttachCurrentThread();
+  ScopedJavaLocalRef<jobject> j_obj = java_ref_.get(env);
+  if (j_obj.is_null())
+    return;
+
+  if (Java_ContentViewCore_onForwardingGestureEvent(
+          env, j_obj.obj(), event.type, event.x, event.y))
+    return;
+
+  RenderWidgetHostViewAndroid* rwhv = GetRenderWidgetHostViewAndroid();
+  if (rwhv)
+    rwhv->SendGestureEvent(event);
+}
+
 RenderWidgetHostViewAndroid*
     ContentViewCoreImpl::GetRenderWidgetHostViewAndroid() {
   RenderWidgetHostView* rwhv = NULL;
@@ -497,20 +540,15 @@ void ContentViewCoreImpl::ShowSelectPopupMenu(
 }
 
 void ContentViewCoreImpl::ConfirmTouchEvent(InputEventAckState ack_result) {
-  JNIEnv* env = AttachCurrentThread();
-  ScopedJavaLocalRef<jobject> j_obj = java_ref_.get(env);
-  if (j_obj.is_null())
-    return;
-  Java_ContentViewCore_confirmTouchEvent(env, j_obj.obj(),
-                                         static_cast<jint>(ack_result));
+  gesture_event_queue_.OnTouchEventAck(ack_result);
 }
 
-void ContentViewCoreImpl::UnhandledFlingStartEvent() {
+void ContentViewCoreImpl::UnhandledFlingStartEvent(float vx, float vy) {
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobject> j_obj = java_ref_.get(env);
   if (j_obj.is_null())
     return;
-  Java_ContentViewCore_unhandledFlingStartEvent(env, j_obj.obj());
+  Java_ContentViewCore_unhandledFlingStartEvent(env, j_obj.obj(), vx, vy);
 }
 
 void ContentViewCoreImpl::OnScrollUpdateGestureConsumed() {
@@ -521,16 +559,6 @@ void ContentViewCoreImpl::OnScrollUpdateGestureConsumed() {
   Java_ContentViewCore_onScrollUpdateGestureConsumed(env, j_obj.obj());
 }
 
-void ContentViewCoreImpl::HasTouchEventHandlers(bool need_touch_events) {
-  JNIEnv* env = AttachCurrentThread();
-  ScopedJavaLocalRef<jobject> j_obj = java_ref_.get(env);
-  if (j_obj.is_null())
-    return;
-  Java_ContentViewCore_hasTouchEventHandlers(env,
-                                             j_obj.obj(),
-                                             need_touch_events);
-}
-
 bool ContentViewCoreImpl::HasFocus() {
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
@@ -896,21 +924,32 @@ void ContentViewCoreImpl::SendOrientationChangeEvent(JNIEnv* env,
   }
 }
 
-jboolean ContentViewCoreImpl::SendTouchEvent(JNIEnv* env,
-                                             jobject obj,
-                                             jlong time_ms,
-                                             jint type,
-                                             jobjectArray pts) {
+void ContentViewCoreImpl::OnTouchEventHandlingBegin(JNIEnv* env,
+                                                    jobject obj,
+                                                    jlong time_ms,
+                                                    jint type,
+                                                    jobjectArray pts) {
+  DCHECK(!handling_touch_event_);
+  handling_touch_event_ = true;
+
+  blink::WebTouchEvent event;
+  TouchPoint::BuildWebTouchEvent(env, type, time_ms, GetDpiScale(), pts, event);
+  pending_touch_event_ = event;
+
+  pending_gesture_packet_ = GestureEventPacket::FromTouch(event);
+}
+
+void ContentViewCoreImpl::OnTouchEventHandlingEnd(JNIEnv* env, jobject obj) {
+  DCHECK(handling_touch_event_);
+  handling_touch_event_ = false;
+
   RenderWidgetHostViewAndroid* rwhv = GetRenderWidgetHostViewAndroid();
-  if (rwhv) {
-    using blink::WebTouchEvent;
-    blink::WebTouchEvent event;
-    TouchPoint::BuildWebTouchEvent(env, type, time_ms, GetDpiScale(), pts,
-        event);
-    rwhv->SendTouchEvent(event);
-    return true;
-  }
-  return false;
+  if (!rwhv)
+    return;
+
+  // Note: Order is important here, as the touch may be ack'ed synchronously
+  gesture_event_queue_.OnGestureEventPacket(pending_gesture_packet_);
+  rwhv->SendTouchEvent(pending_touch_event_);
 }
 
 float ContentViewCoreImpl::GetTouchPaddingDip() {
@@ -980,9 +1019,18 @@ WebGestureEvent ContentViewCoreImpl::MakeGestureEvent(
 
 void ContentViewCoreImpl::SendGestureEvent(
     const blink::WebGestureEvent& event) {
-  RenderWidgetHostViewAndroid* rwhv = GetRenderWidgetHostViewAndroid();
-  if (rwhv)
-    rwhv->SendGestureEvent(event);
+  if (handling_touch_event_) {
+    pending_gesture_packet_.Push(event);
+    return;
+  }
+  gesture_event_queue_.OnGestureEventPacket(
+      GestureEventPacket::FromGesture(ToGestureSource(event), event));
+}
+
+void ContentViewCoreImpl::SendSyntheticGestureEvent(
+    const blink::WebGestureEvent& event) {
+  gesture_event_queue_.OnGestureEventPacket(
+      GestureEventPacket::FromGesture(GestureEventPacket::SYNTHETIC, event));
 }
 
 void ContentViewCoreImpl::ScrollBegin(JNIEnv* env,
@@ -1042,12 +1090,14 @@ void ContentViewCoreImpl::SingleTap(JNIEnv* env, jobject obj, jlong time_ms,
       WebInputEvent::GestureTap, time_ms, x, y);
 
   event.data.tap.tapCount = 1;
-  if (!disambiguation_popup_tap) {
-    const float touch_padding_dip = GetTouchPaddingDip();
-    event.data.tap.width = touch_padding_dip;
-    event.data.tap.height = touch_padding_dip;
+  if (disambiguation_popup_tap) {
+    SendSyntheticGestureEvent(event);
+    return;
   }
 
+  const float touch_padding_dip = GetTouchPaddingDip();
+  event.data.tap.width = touch_padding_dip;
+  event.data.tap.height = touch_padding_dip;
   SendGestureEvent(event);
 }
 
@@ -1105,12 +1155,14 @@ void ContentViewCoreImpl::LongPress(JNIEnv* env, jobject obj, jlong time_ms,
   WebGestureEvent event = MakeGestureEvent(
       WebInputEvent::GestureLongPress, time_ms, x, y);
 
-  if (!disambiguation_popup_tap) {
-    const float touch_padding_dip = GetTouchPaddingDip();
-    event.data.longPress.width = touch_padding_dip;
-    event.data.longPress.height = touch_padding_dip;
+  if (disambiguation_popup_tap) {
+    SendSyntheticGestureEvent(event);
+    return;
   }
 
+  const float touch_padding_dip = GetTouchPaddingDip();
+  event.data.longPress.width = touch_padding_dip;
+  event.data.longPress.height = touch_padding_dip;
   SendGestureEvent(event);
 }
 
@@ -1120,12 +1172,14 @@ void ContentViewCoreImpl::LongTap(JNIEnv* env, jobject obj, jlong time_ms,
   WebGestureEvent event = MakeGestureEvent(
       WebInputEvent::GestureLongTap, time_ms, x, y);
 
-  if (!disambiguation_popup_tap) {
-    const float touch_padding_dip = GetTouchPaddingDip();
-    event.data.longPress.width = touch_padding_dip;
-    event.data.longPress.height = touch_padding_dip;
+  if (disambiguation_popup_tap) {
+    SendSyntheticGestureEvent(event);
+    return;
   }
 
+  const float touch_padding_dip = GetTouchPaddingDip();
+  event.data.longPress.width = touch_padding_dip;
+  event.data.longPress.height = touch_padding_dip;
   SendGestureEvent(event);
 }