Handle mac trackpad zoom via GesturePinch events

content/browser/renderer_host/input/input_router_impl.cc

 // Copyright 2013 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/input_router_impl.h"
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 224 matching lines @@
   gesture_event_queue_->FlingHasBeenHalted();
 
   // Only forward the non-native portions of our event.
   FilterAndSendWebInputEvent(key_event, latency_info, is_keyboard_shortcut);
 }
 
 void InputRouterImpl::SendGestureEvent(
     const GestureEventWithLatencyInfo& original_gesture_event) {
   event_stream_validator_.OnEvent(original_gesture_event.event);
   GestureEventWithLatencyInfo gesture_event(original_gesture_event);
+
   if (touch_action_filter_.FilterGestureEvent(&gesture_event.event))
     return;
 
   touch_event_queue_->OnGestureScrollEvent(gesture_event);
 
   if (!IsInOverscrollGesture() &&
       !gesture_event_queue_->ShouldForward(gesture_event)) {
     OverscrollController* controller = client_->GetOverscrollController();
     if (controller)
       controller->DiscardingGestureEvent(gesture_event.event);
@@ skipping 157 matching lines @@
 
   // Any input event cancels a pending mouse move event.
   next_mouse_move_.reset();
 
   OfferToHandlers(input_event, latency_info, is_keyboard_shortcut);
 }
 
 void InputRouterImpl::OfferToHandlers(const WebInputEvent& input_event,
                                       const ui::LatencyInfo& latency_info,
                                       bool is_keyboard_shortcut) {
+  // Trackpad pinch gestures are not yet handled by the renderer.

[jdduke (slow), 2014/03/27 02:08:02]

Is that true? The compositor currently doesn't distinguish between source types
when dispatching GesturePinchUpdate
(https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/i...).
 However, maybe that's simply because we don't have any platforms (yet) that
provide such gestures via the trackpad?

As long as this is the behavior we want on *all* platforms, the router is
probably as good as any place for this.

+  // TODO(rbyers): Send mousewheel for trackpad pinch - crbug.com/289887.
+  if (input_event.type == WebInputEvent::GesturePinchUpdate &&
+      static_cast<const WebGestureEvent&>(input_event).sourceDevice ==
+          WebGestureEvent::Touchpad) {
+    ProcessInputEventAck(input_event.type,
+                         INPUT_EVENT_ACK_STATE_NOT_CONSUMED,
+                         latency_info,
+                         ACK_SOURCE_NONE);
+    return;
+  }
+
   if (OfferToOverscrollController(input_event, latency_info))
     return;
 
   if (OfferToClient(input_event, latency_info))
     return;
 
   OfferToRenderer(input_event, latency_info, is_keyboard_shortcut);
 
   // If we don't care about the ack disposition, send the ack immediately.
   if (WebInputEventTraits::IgnoresAckDisposition(input_event.type)) {
@@ skipping 375 matching lines @@
   touch_event_queue_->SetAckTimeoutEnabled(touch_ack_timeout_enabled,
                                            touch_ack_timeout_delay_);
 }
 
 bool InputRouterImpl::IsInOverscrollGesture() const {
   OverscrollController* controller = client_->GetOverscrollController();
   return controller && controller->overscroll_mode() != OVERSCROLL_NONE;
 }
 
 }  // namespace content