Extract key press and release handling out of previewKey() to
KeyDebouncer class. And pass Key object as argument of previewKey()
instead of key index.

Bug: 2910379
Change-Id: Ifec39cfc4845bd92da2f62eba2b26ac6a5cbb341

These three conditions assign true to the mAbortKey flag.
1. setKeyboard() sets the new keyboard layout.
2. long press shows the pop-up mini keyboard.
3. ACTION_CANCEL event is occurred.

In the case 1, in LatinIME so far, only "symbol key" and "language
switch" cause keyboard layout change.  In both cases, the event is
occurred in onUpEvent(), so we do not need to worry about aborting
event.

In the case 2, long press is used only to pop-up mini-keyboard and at that
time mMiniKeyboardOnScreen could be used as a flag.

In the case 3, though I'm not sure when this case occurs, in
onCancelEvent() all the things that should be canceled are canceled
in onCancelEvent().

Bug: 2910379
Change-Id: I12377c5f3e808f1c017ce980e12b1513895047bc

This change also re-orders instance variables and eliminates
unnecessary ones.

Bug: 2910379
Change-Id: I6b2217f75738fada32a33f59f0f7adba5e99dd6e

This reverts commit 09f530e2.

Change-Id: I3106cd22cc1eac750f05bce26df6af3026dfaf86

This change will display the key board preview instantaneously when
the key is pressed.  Dismissing the key preview will be delayed
slightly after the key is released, as we do now.

Because in multi touch mode, we should instantaneously change keyboard
layout when modifier key, such as shit and symbol, is pressed.

Change-Id: I49348d563ca0f40f5a0a236bdcd0bb07eedd599b

This change eliminates the need of extra MotionEvent allocation.  Also
this will lead to the easy way to handle multi touch events.

Bug: 2910379
Change-Id: Ibcfcba554b732c13105f91877b41b553ee6928ba

Bug: 2910379
Change-Id: Ib26a898ea108ee4292f9f91b6d7d10c1fc380fd1

This change moves SwipeTracker out from LatinKeyboardBaseView.  Also
this introduces EventBuffer class for swipe tracking buffer.

Bug: 2910379

Change-Id: I48ff714226a248ca063cbaf9755cf45e458f7402

Change-Id: I57cc6fb6a9eeb65ce8c0c3c3262fd525726643e2

GestureDetector listener's onFling method will not call detectAndSendKey
anymore.

Make gesture detector be ignoring multitouch.  Refactoring
GestureDetector out of LatinKeyboardBaseView class change will follow.

Bug: 2910379
Change-Id: I0b2a9c4cf7d432f89f9085f3c2bdf3a3757a8903

Bug: 2950714
Change-Id: I3110369c085f89ee1e8f7392a9a04a6b9e377ed4

Bug: 2910379
Change-Id: If0ef09d8b0e7ca1c62b4c5a31bcaa620664868f2

This change encapsulates mInKeyRepeat (former mRepeatKeyIndex) into
UIHandler class.  Also this eliminates mCurrentKey and mLastTapTime
dependency from repeatKey method.

Bug: 2910379
Change-Id: I9351a558be2ebc04de4ebb0d323af4be33bd470c

This change eliminates mCurrentKey dependency from openPopupIfRequired
method.  Also slightly cleanup onModifiedTouchEvent.

Bug: 2910379
Change-Id: I90c9b39c46c0bb32ecc6588abfc49eb60315f54c

This change simplifies onModifierTouchEvent to focus on handling
motion event related to a key event.

Other refactoring will follow in order to support multi touch.

Bug: 2910379

Change-Id: I036be64168d951a535600a7910b36bc109f88490

TODO: Cleanup will follow.

Change-Id: I4a68ba9f2f55760aa24187f1f13fdfa8a0b70963