Set the coordinates of the synthetic touch event correctly in SyntheticGestureTargetAura

content/browser/renderer_host/input/synthetic_gesture_target_aura.cc

Index: content/browser/renderer_host/input/synthetic_gesture_target_aura.cc
diff --git a/content/browser/renderer_host/input/synthetic_gesture_target_aura.cc b/content/browser/renderer_host/input/synthetic_gesture_target_aura.cc
index 64e1c16b9f72172561d84f1da9cb712e9c378fa6..ac0dc6b71f05e4bf335cb9371bd408205ebcd6eb 100644
--- a/content/browser/renderer_host/input/synthetic_gesture_target_aura.cc
+++ b/content/browser/renderer_host/input/synthetic_gesture_target_aura.cc
@@ -11,6 +11,7 @@
 #include "content/browser/renderer_host/ui_events_helper.h"
 #include "third_party/WebKit/public/platform/WebScreenInfo.h"
 #include "ui/aura/window.h"
+#include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/events/event_processor.h"
 #include "ui/events/event_utils.h"
@@ -37,15 +38,20 @@ void SyntheticGestureTargetAura::DispatchWebTouchEventToPlatform(
     touch_with_latency.event.touches[i].position.x *= device_scale_factor_;
     touch_with_latency.event.touches[i].position.y *= device_scale_factor_;
     touch_with_latency.event.touches[i].radiusX *= device_scale_factor_;
-    touch_with_latency.event.touches[i].radiusY *= device_scale_factor_;
+    touch_with_latency.event.touches[i].radiusY *= device_scale_factor_;;

[tdresser, 2016/08/24 12:27:48]

Remove extra ;

[lanwei, 2016/08/25 02:28:55]

Done.

   }
   ScopedVector<ui::TouchEvent> events;
   bool conversion_success = MakeUITouchEventsFromWebTouchEvents(
-      touch_with_latency, &events, LOCAL_COORDINATES);
+      touch_with_latency, &events, SCREEN_COORDINATES);

[bokan, 2016/08/24 15:56:57]

Why is this change needed? The call below to ConvertLocationToTarget seems to
imply we're going from one set of window coordinates to another, rather than any
screen coordinates. It happens that on Android screen coordinates are window
coordinates (perhaps off by the system toolbar) but I wonder if this breaks on
desktops.

[lanwei, 2016/08/25 02:28:55]

Actually for SyntheticTouchEvents, the screen position and position are set to
the same. like point.position.x = point.screenPosition.x = x;, so I guess it
would not make much difference.

[bokan, 2016/08/25 12:36:51]

Ugh, it looks like the synthetic gestures don't really set screen position
properly. That seems problematic to me but that's not a fault in this patch.
Anyway, I'd leave this as LOCAL_COORDINATES (as you currently have) since the
screen coordinates are sometimes set to 0. (e.g.
https://cs.chromium.org/chromium/src/content/common/input/synthetic_web_input...)

   DCHECK(conversion_success);
 
   aura::Window* window = GetWindow();
   aura::WindowTreeHost* host = window->GetHost();
+
+  // Synthetic touch events will be transformed here before send to

[tdresser, 2016/08/24 12:27:48]

before being sent to the EventProcessor

[lanwei, 2016/08/25 02:28:55]

Done.

+  // EventProcessor, so it should not be transformed again later in

[tdresser, 2016/08/24 12:27:49]

so they should not be transformed again later

[lanwei, 2016/08/25 02:28:55]

Done.

+  // WindowEventDispatcher.
+  host->dispatcher()->set_transform_events(false);
   for (ScopedVector<ui::TouchEvent>::iterator iter = events.begin(),
       end = events.end(); iter != end; ++iter) {
     (*iter)->ConvertLocationToTarget(window, host->window());