Add display::GetDisplayNearestView

content/browser/renderer_host/render_widget_host_view_base.cc

Index: content/browser/renderer_host/render_widget_host_view_base.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_base.cc b/content/browser/renderer_host/render_widget_host_view_base.cc
index d09da0790d0df887ac8265565c89e265dfe90e46..806714e00d447e5431dc5de7779184ac64c95d30 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.cc
+++ b/content/browser/renderer_host/render_widget_host_view_base.cc
@@ -16,11 +16,13 @@
 #include "content/browser/renderer_host/render_widget_host_view_frame_subscriber.h"
 #include "content/browser/renderer_host/text_input_manager.h"
 #include "content/common/content_switches_internal.h"
+#include "ui/base/layout.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 #include "ui/gfx/geometry/point_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/geometry/size_f.h"
+#include "ui/gfx/view_util.h"
 
 namespace content {
 
@@ -104,7 +106,9 @@ bool RenderWidgetHostViewBase::GetBackgroundOpaque() {
 
 gfx::Size RenderWidgetHostViewBase::GetPhysicalBackingSize() const {
   display::Display display =
-      display::Screen::GetScreen()->GetDisplayNearestWindow(GetNativeView());
+      display::Screen::GetScreen()->GetDisplayNearestWindow(
+          gfx::GetTopLevel(GetNativeView()));
+
   return gfx::ScaleToCeiledSize(GetRequestedRendererSize(),
                                 display.device_scale_factor());
 }
@@ -263,7 +267,8 @@ void RenderWidgetHostViewBase::UpdateScreenInfo(gfx::NativeView view) {
 
 bool RenderWidgetHostViewBase::HasDisplayPropertyChanged(gfx::NativeView view) {
   display::Display display =
-      display::Screen::GetScreen()->GetDisplayNearestWindow(view);
+      display::Screen::GetScreen()->GetDisplayNearestWindow(
+          gfx::GetTopLevel(view));
   if (current_display_area_ == display.work_area() &&
       current_device_scale_factor_ == display.device_scale_factor() &&
       current_display_rotation_ == display.rotation()) {
@@ -311,6 +316,10 @@ void RenderWidgetHostViewBase::FocusedNodeTouched(
   DVLOG(1) << "FocusedNodeTouched: " << editable;
 }
 
+float RenderWidgetHostViewBase::GetScaleFactorForNativeView() const {
+  return ui::GetScaleFactorForNativeWindow(gfx::GetTopLevel(GetNativeView()));

[tapted, 2017/02/15 00:36:10]

if callers still need the virtual method in RWHV, this should probably just be
return current_device_scale_factor_;   (content OWNERS might have other ideas
though)

That is, after stuff that has (or is) a RenderWidgetHostViewBase is using
current_device_scale_factor(), the remaining things outside of content wanting
GetScaleFactorForNativeView() can probably just go back to what they were doing
before. 

However, those methods are a LOT more expensive than just using
current_device_scale_factor_ .

For example, in ScreenMac::GetDisplayNearestWindow() has a comment

    // Note the following line calls -[NSWindow
    // _bestScreenBySpaceAssignmentOrGeometry] which is quite expensive and
    // performs IPC with the window server process.
    NSScreen* match_screen = [window screen];

it would be nice to avoid that.


i.e. my vote would be to use a content-public/exported virtual method on
RenderWidgetHostView that just returns current_device_scale_factor_ here.

But there's usually a resistance to adding new content-public methods. You'll
need a content OWNER for this.

[Jinsuk Kim, 2017/02/16 10:11:25]

Thanks for the suggestion. Done as suggested. I think the new method is useful
so I'm hoping its addition is justifiable.

+}
+
 uint32_t RenderWidgetHostViewBase::RendererFrameNumber() {
   return renderer_frame_number_;
 }