[Android] Perform haptic feedback after long press when appropriate

content/browser/renderer_host/input/touch_selection_controller.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/input/touch_selection_controller.h"
 
 #include "base/logging.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 
 namespace content {
@@ skipping 165 matching lines @@
   if (is_selection_active_) {
     bool needs_animate = start_selection_handle_->Animate(frame_time);
     needs_animate |= end_selection_handle_->Animate(frame_time);
     return needs_animate;
   }
 
   return false;
 }
 
 void TouchSelectionController::OnHandleDragBegin(const TouchHandle& handle) {
+  last_input_event_type_ = INPUT_EVENT_TYPE_NONE;
+
   if (&handle == insertion_handle_.get()) {
     client_->OnSelectionEvent(INSERTION_DRAG_STARTED, handle.position());
     return;
   }
 
   if (&handle == start_selection_handle_.get()) {
     fixed_handle_position_ = end_selection_handle_->position() -
                              gfx::Vector2dF(0, GetEndLineHeight() / 2.f);
   } else {
     fixed_handle_position_ = start_selection_handle_->position() -
@@ skipping 121 matching lines @@
     start_selection_handle_->SetOrientation(start_orientation_);
   }
 
   if (!end_selection_handle_) {
     end_selection_handle_.reset(new TouchHandle(this, end_orientation_));
   } else {
     end_selection_handle_->SetEnabled(true);
     end_selection_handle_->SetOrientation(end_orientation_);
   }
 
-  if (!is_selection_active_) {
+  // As a long press received while a selection is already active may trigger
+  // an entirely new selection, notify the client but avoid sending an
+  // intervening SELECTION_CLEARED update to avoid unnecessary state changes.
+  if (!is_selection_active_ || last_input_event_type_ == LONG_PRESS) {

[cjhopman, 2014/08/14 00:12:28]

Maybe there's a better name for last_input_event_type_, maybe
pending_input_event_type_ or response_pending_input_event_type_. 

Should this be reset to NONE on other events that might signify that it is done?


Should we have a more robust way of determining that a particular event (or type
of event) caused a selection change?

[jdduke (slow), 2014/08/14 17:57:19]

Yeah, I'll tweak it.
Yes.
Yeah, the current attempt is both lazy and imprecise.  I've put in a hard reset
of the event any time the selection changes.  That still doesn't guarantee the
change came from a gesture; that would probably involve wiring the causal change
from Blink to be truly accurate.

     is_selection_active_ = true;
+    last_input_event_type_ = INPUT_EVENT_TYPE_NONE;
     client_->OnSelectionEvent(SELECTION_SHOWN, GetStartPosition());
   }
 }
 
 void TouchSelectionController::DeactivateSelection() {
   if (!is_selection_active_)
     return;
   DCHECK(start_selection_handle_);
   DCHECK(end_selection_handle_);
   start_selection_handle_->SetEnabled(false);
@@ skipping 38 matching lines @@
 }
 
 TouchHandle::AnimationStyle TouchSelectionController::GetAnimationStyle(
     bool was_active) const {
   return was_active && client_->SupportsAnimation()
              ? TouchHandle::ANIMATION_SMOOTH
              : TouchHandle::ANIMATION_NONE;
 }
 
 }  // namespace content