Explicitly suppress scrolling for wheel events that will trigger zooming

content/common/input/synthetic_web_input_event_builders.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/common/input/synthetic_web_input_event_builders.h"
 
 #include "base/logging.h"
 #include "content/common/input/web_touch_event_traits.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 
@@ skipping 50 matching lines @@
   WebMouseWheelEvent result;
   result.type = WebInputEvent::MouseWheel;
   result.deltaX = dx;
   result.deltaY = dy;
   if (dx)
     result.wheelTicksX = dx > 0.0f ? 1.0f : -1.0f;
   if (dy)
     result.wheelTicksY = dy > 0.0f ? 1.0f : -1.0f;
   result.modifiers = modifiers;
   result.hasPreciseScrollingDeltas = precise;
+  if ((modifiers & blink::WebInputEvent::ControlKey) && !precise) {

[Rick Byers, 2014/12/12 22:20:29]

Which tests fail if you just unconditionally set canScroll to true here?  It's a
little odd that we're baking Aura's logic into the syntehtic event builders used
by tests - even on Mac where the logic doesn't apply.

Ideally your CL would need to update WebContentsImplTest::HandleWheelEvent to
explicitly set canScroll to false on the event.  Then you'd also be able to test
that a canScroll=true event doesn't ever also cause zooming.

In particular, look at the part of the test that says "Events containing precise
scrolling deltas also shouldn't result in ...".  Previously it was testing
something valuable.  Now after your CL it's really testing the behavior of the
synthetic event building code here, not the code in the product that actually
pays attention to hasPreciseDeltas!

[lanwei, 2014/12/17 23:16:40]

Done.

+    result.canScroll = false;
+  }
   return result;
 }
 
 WebKeyboardEvent SyntheticWebKeyboardEventBuilder::Build(
     WebInputEvent::Type type) {
   DCHECK(WebInputEvent::isKeyboardEventType(type));
   WebKeyboardEvent result;
   result.type = type;
   result.windowsKeyCode = ui::VKEY_L;  // non-null made up value.
   return result;
@@ skipping 121 matching lines @@
   touches[index].state = WebTouchPoint::StateCancelled;
   WebTouchEventTraits::ResetType(
       WebInputEvent::TouchCancel, timeStampSeconds, this);
 }
 
 void SyntheticWebTouchEvent::SetTimestamp(base::TimeDelta timestamp) {
   timeStampSeconds = timestamp.InSecondsF();
 }
 
 }  // namespace content