Convert MouseEvents from DIPS to Pixels before passing it to surfaces for hittesting.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 96cfc510dc14128fa6a06fa56334fd0c15fa7418..2ab4e5d2dbc8121cc0c8b44569ead4a28bc4ebd4 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -80,6 +80,7 @@
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/color_profile.h"
 #include "ui/gfx/display.h"
+#include "ui/gfx/geometry/dip_util.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/screen.h"
@@ -2167,8 +2168,15 @@ void RenderWidgetHostViewAura::OnMouseEvent(ui::MouseEvent* event) {
 uint32_t RenderWidgetHostViewAura::SurfaceIdNamespaceAtPoint(
     const gfx::Point& point,
     gfx::Point* transformed_point) {
-  cc::SurfaceId id =
-      delegated_frame_host_->SurfaceIdAtPoint(point, transformed_point);
+  const gfx::Display display = window_ ?

[sadrul, 2015/10/21 21:46:21]

When can |window_| be null here?

+      gfx::Screen::GetScreenFor(window_)->GetDisplayNearestWindow(window_) :
+      gfx::Screen::GetScreenFor(window_)->GetPrimaryDisplay();
+  float scale_factor = display.device_scale_factor();

[sadrul, 2015/10/21 21:46:21]

How often do we have to do this? Would it make sense to cache the scale-factor
in RWHVA (and update in OnDeviceScaleFactorChanged() override)?

+  gfx::Point point_in_pixels = gfx::ConvertPointToPixel(scale_factor, point);
+  cc::SurfaceId id = delegated_frame_host_->SurfaceIdAtPoint(point_in_pixels,
+                                                             transformed_point);
+  *transformed_point = gfx::ConvertPointToDIP(scale_factor, *transformed_point);
+
   // It is possible that the renderer has not yet produced a surface, in which
   // case we return our current namespace.
   if (id.is_null())