Fix tab drag and drop with hi-dpi.

ui/views/widget/desktop_aura/desktop_screen_x11.cc

Index: ui/views/widget/desktop_aura/desktop_screen_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_screen_x11.cc b/ui/views/widget/desktop_aura/desktop_screen_x11.cc
index ed8a0f4844cd7f002c6d1c492eff05575ebedf81..a7ea43af543a4e54d926d12d444184b58dd253f8 100644
--- a/ui/views/widget/desktop_aura/desktop_screen_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_screen_x11.cc
@@ -45,6 +45,19 @@ float GetDeviceScaleFactor(int screen_pixels, int screen_mm) {
   return ui::GetScaleForScaleFactor(ui::GetSupportedScaleFactor(scale));
 }
 
+float GetDeviceScaleFactor() {
+  gfx::Display display = gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
+  return display.device_scale_factor();
+}
+
+gfx::Point ScreenToDIPPoint(const gfx::Point& pixel_point) {

[sadrul, 2015/03/17 15:56:06]

Let's call this ToDIPPoint, or PixelToDIPPoint.

In some places of the codebase, we use 'DIP in screen space', and so 'Screen' by
itself does not necessarily mean physical pixels. PixelToDIPPoint() (or simply
ToDIPPoint()) would make that clearer.

[stapelberg, 2015/03/19 08:25:44]

Done.

+  return ToFlooredPoint(ScalePoint(pixel_point, 1.0f / GetDeviceScaleFactor()));
+}
+
+gfx::Point DIPToScreenPoint(const gfx::Point& dip_point) {
+  return ToFlooredPoint(gfx::ScalePoint(dip_point, GetDeviceScaleFactor()));
+}
+

[sadrul, 2015/03/17 15:56:06]

Is there any way we can avoid dup'ing this block of code between the two files?

[stapelberg, 2015/03/19 08:25:44]

I wouldn’t know how, if not by introducing yet another file that contains these
functions. At that point we’d have ui/compositor/dip_util and ui/gfx/win/dpi and
our new file doing the same thing. I think it’d be worthwhile to clean this up
across chromium, but I feel like that’s out of scope for the bugfix I’m trying
to get in :).

I tried using ash::Shell::GetPrimaryRootWindow so that I can use
ui/compositor/dip_util, but that didn’t work, chromium crashes with the
following backtrace when I try that:

#0  0x00007ffff177a8c7 in raise () at /lib64/libc.so.6
#1  0x00007ffff177c52a in abort () at /lib64/libc.so.6
#2  0x0000555556553956 in  ()
#3  0x00005555565672e8 in logging::LogMessage::~LogMessage() ()
#4  0x000055555840a9c5 in ash::Shell::GetPrimaryRootWindow() ()
#5  0x0000555558c0b0f6 in views::DesktopScreenX11::GetCursorScreenPoint() ()
#6  0x0000555558558ca6 in
content::RenderWidgetHostViewAura::UpdateCursorIfOverSelf() ()
#7  0x000055555854824c in content::RenderViewHostImpl::SetIsLoading(bool) ()
#8  0x00005555584d3add in content::RenderFrameHostManager::SetIsLoading(bool) ()
#9  0x00005555585dc0f1 in
content::WebContentsImpl::SetIsLoading(content::RenderViewHost*, bool, bool,
content::LoadNotificationDetails*) ()
#10 0x00005555585df3c0 in non-virtual thunk to
content::WebContentsImpl::DidStartLoading(content::RenderFrameHost*, bool) ()
#11 0x00005555584cf730 in
content::RenderFrameHostImpl::Navigate(content::CommonNavigationParams const&,
content::StartNavigationParams const&, content::CommitNavigationParams const&,
content::HistoryNavigationParams const&) ()
#12 0x00005555586ae007 in
content::NavigatorImpl::NavigateToEntry(content::FrameTreeNode*,
content::NavigationEntryImpl const&, content::NavigationController::ReloadType)
()
#13 0x00005555584c0c53 in
content::NavigationControllerImpl::NavigateToPendingEntry(content::NavigationController::ReloadType)
()
#14 0x00005555584c0eea in
content::NavigationControllerImpl::LoadEntry(content::NavigationEntryImpl*) ()
#15 0x00005555584c1937 in
content::NavigationControllerImpl::LoadURLWithParams(content::NavigationController::LoadURLParams
const&) ()
#16 0x00005555580dc819 in (anonymous
namespace)::LoadURLInContents(content::WebContents*, GURL const&,
chrome::NavigateParams*) ()
#17 0x00005555580dc0a1 in chrome::Navigate(chrome::NavigateParams*) ()
#18 0x00005555581e2fea in StartupBrowserCreatorImpl::OpenTabsInBrowser(Browser*,
bool, std::vector<StartupTab, std::allocator<StartupTab> > const&,
chrome::HostDesktopType) ()
#19 0x00005555581e210f in
StartupBrowserCreatorImpl::ProcessSpecifiedURLs(std::vector<GURL,
std::allocator<GURL> > const&, chrome::HostDesktopType) ()
#20 0x00005555581e1dd6 in
StartupBrowserCreatorImpl::ProcessStartupURLs(std::vector<GURL,
std::allocator<GURL> > const&, chrome::HostDesktopType) ()
#21 0x00005555581e139d in StartupBrowserCreatorImpl::ProcessLaunchURLs(bool,
std::vector<GURL, std::allocator<GURL> > const&, chrome::HostDesktopType) ()
#22 0x00005555581e0960 in StartupBrowserCreatorImpl::Launch(Profile*,
std::vector<GURL, std::allocator<GURL> > const&, bool, chrome::HostDesktopType)
()
#23 0x00005555581de7ac in StartupBrowserCreator::LaunchBrowser(base::CommandLine
const&, Profile*, base::FilePath const&, chrome::startup::IsProcessStartup,
chrome::startup::IsFirstRun) ()
#24 0x00005555581de16d in
StartupBrowserCreator::ProcessCmdLineImpl(base::CommandLine const&,
base::FilePath const&, bool, Profile*, std::vector<Profile*,
std::allocator<Profile*> > const&, StartupBrowserCreator*) ()
#25 0x00005555581dcb18 in StartupBrowserCreator::Start(base::CommandLine const&,
base::FilePath const&, Profile*, std::vector<Profile*, std::allocator<Profile*>
> const&) ()
#26 0x000055555626bc7b in ChromeBrowserMainParts::PreMainMessageLoopRunImpl() ()
#27 0x000055555626a992 in ChromeBrowserMainParts::PreMainMessageLoopRun() ()
#28 0x000055555866f6a9 in content::BrowserMainLoop::PreMainMessageLoopRun() ()
#29 0x0000555558754b47 in content::StartupTaskRunner::RunAllTasksNow() ()
#30 0x000055555866de1e in content::BrowserMainLoop::CreateStartupTasks() ()
#31 0x000055555848b244 in
content::BrowserMainRunnerImpl::Initialize(content::MainFunctionParams const&)
()
#32 0x000055555848af8d in content::BrowserMain(content::MainFunctionParams
const&) ()
#33 0x00005555564fb2b5 in content::ContentMainRunnerImpl::Run() ()
#34 0x00005555564f9f10 in content::ContentMain(content::ContentMainParams
const&) ()
#35 0x0000555555fe7c68 in ChromeMain ()
#36 0x00007ffff1765fe0 in __libc_start_main () at /lib64/libc.so.6
#37 0x0000555555fe7b1f in _start ()

So, in conclusion, unless you see an easy way, I’d ask you to push this
refactoring off for later.

 std::vector<gfx::Display> GetFallbackDisplayList() {
   ::XDisplay* display = gfx::GetXDisplay();
   ::Screen* screen = DefaultScreenOfDisplay(display);
@@ -130,7 +143,7 @@ gfx::Point DesktopScreenX11::GetCursorScreenPoint() {
                 &win_y,
                 &mask);
 
-  return gfx::Point(root_x, root_y);
+  return ScreenToDIPPoint(gfx::Point(root_x, root_y));
 }
 
 gfx::NativeWindow DesktopScreenX11::GetWindowUnderCursor() {
@@ -177,7 +190,8 @@ gfx::Display DesktopScreenX11::GetDisplayNearestWindow(
 }
 
 gfx::Display DesktopScreenX11::GetDisplayNearestPoint(
-    const gfx::Point& point) const {
+    const gfx::Point& requested_point) const {
+  const gfx::Point point = DIPToScreenPoint(requested_point);

[sadrul, 2015/03/17 15:56:06]

point_in_pixel

[stapelberg, 2015/03/19 08:25:44]

Done.

   for (std::vector<gfx::Display>::const_iterator it = displays_.begin();
        it != displays_.end(); ++it) {
     if (it->bounds().Contains(point))