Pass TouchAction bits together with rect in SetTouchEventHandlerRegion

third_party/WebKit/public/platform/WebTouchActionRect.h

+// Copyright 2017 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.
+
+#ifndef WebTouchActionRect_h
+#define WebTouchActionRect_h
+
+#include "WebRect.h"
+
+namespace blink {
+
+// WebTouchInfo stores a rect with its corresponding touch action, which will

[wkorman, 2017/05/03 20:02:14]

WebTouchInfo -> WebTouchActionRect (if we keep the name as WebTouchActionRect)

[xidachen, 2017/05/04 12:11:21]

Changed to WebTouchInfo.

+// be passed to CC through WebLayer::SetTouchEventHandlerRegion.

[wkorman, 2017/05/03 20:02:14]

Would remove the bit about "which will be passed..." since the code path/methods
can change down the line and easy to forget to update comments. Generally prefer
comments to focus on behavior/functionality.

[xidachen, 2017/05/04 12:11:21]

comments updated.

+struct WebTouchActionRect {
+  WebRect rect;
+
+  // Reason of using int instead of WebTouchAction: WebTouchActionRect will be
+  // used as a parameter in WebLayer::SetTouchEventHandlerRegion which means
+  // this file has to live under public/platform/. We cannot include
+  // WebTouchAction because that lives under public/web/.
+  int touch_action;

[wkorman, 2017/05/03 20:02:14]

I think we can use an enum here, following pattern we use for element_id.h and
CompositorElementId.h.

You can explore that if you'd like, or I am ok landing this in interim and you
can focus on the cc side logic, but if we do that let's update the comment to
note that this is temporary while we explore that.

To elaborate, I think to do it we'll have to do something like:
1. define yet another copy of the enum under cc/ dir somewhere. This will really
just be moving the existing Blink definition detail (more below).
2. define a new Blink-side TouchAction class under platform/graphics or similar
that uses 'using' to extend with a Blink-specific class name
3. delete WebTouchAction class and change all usages to use the class we defined
in (2) instead.

There may be some trickiness though because there is a bunch of core/style usage
of the 'enum TouchAction' defined in core/style/ComputedStyleConstants.h, and
I'd hope we can get rid of that enum and have core/style use the one we define
in (2) as well, but it's possible I'm not yet aware of some dependency issue
we'll have to resolve.

Crazily it appears there are at least three exact copies of the enum today:
a. content/common/input/touch_action.h
b. third_party/WebKit/Source/public/web/WebTouchAction.h
c. third_party/WebKit/Source/core/style/ComputedStyleConstants.h

and even more crazily, code in public/web and content just does a straight
static_cast from one enum type to another.

So given the complexity (I am amidst unwinding/understanding all of the above,
have been researching the code) I support going with this interim patch if you'd
prefer.

[xidachen, 2017/05/04 12:11:21]

I think I would prefer landing a simple patch first and investigate on two
things:
1). Unify TouchAction classes.
2). Get rid of the WebLayer class as I mentioned before.

WDYT?

+};
+
+}  // namespace blink
+
+#endif