Fixed tab dragging which was broken on high DPI windows for scales other than 100%.

The tab dragging code uses the GetCursorPos API to determine the tab strip to be used
to drag the tab into. This API returns values in pixel. We need to convert to DIP and
vice versa wherever needed.

Changes as below:-
1. window_finder_win.cc :- The cursor position after my changes now comes in as DIP.
                           We need to convert to pixel as this class uses PtInRect
                           and other APIs which need values in pixel.
2. screen_win.cc :- The GetCursorScreenPoint now returns values in DIP which is what is
                    expected. These values are passed to views and other places which
                    expect values in DIP.
3. apps_grid_view.cc :- Converted cursor position to DIP before passing it to the views code.

Looked at other usages of this API. They seem to be in order. Thought about adding helpers for
this for Windows. Decided against it as it is very hard to enforce given that it is a popular
API.

BUG=364969
R=sky@chromium.org, sky

Review URL: https://codereview.chromium.org/256923002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266744 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/views/tabs/window_finder_win.cc

@@ -8,6 +8,7 @@
 #include "base/win/windows_version.h"
 #include "ui/aura/window.h"
 #include "ui/gfx/screen.h"
+#include "ui/gfx/win/dpi.h"
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host_win.h"
 #include "ui/views/win/hwnd_util.h"
 
@@ -126,16 +127,16 @@ class TopMostFinder : public BaseWindowFinder {
                 const std::set<HWND>& ignore)
       : BaseWindowFinder(ignore),
         target_(window),
-        screen_loc_(screen_loc),
         is_top_most_(false),
         tmp_region_(CreateRectRgn(0, 0, 0, 0)) {
+    screen_loc_ = gfx::win::DIPToScreenPoint(screen_loc);
     EnumWindows(WindowCallbackProc, as_lparam());
   }
 
   // The window we're looking for.
   HWND target_;
 
-  // Location of window to find.
+  // Location of window to find in pixel coordinates.
   gfx::Point screen_loc_;
 
   // Is target_ the top most window? This is initially false but set to true
@@ -165,7 +166,8 @@ class LocalProcessWindowFinder : public BaseWindowFinder {
     if (finder.result_ &&
         ((base::win::OSInfo::GetInstance()->version() >=
           base::win::VERSION_WIN8) ||
-         TopMostFinder::IsTopMostWindowAtPoint(finder.result_, screen_loc,
+         TopMostFinder::IsTopMostWindowAtPoint(finder.result_,
+                                               screen_loc,
                                                ignore))) {
       return views::DesktopWindowTreeHostWin::GetContentWindowForHWND(
           finder.result_);
@@ -188,12 +190,12 @@ class LocalProcessWindowFinder : public BaseWindowFinder {
   LocalProcessWindowFinder(const gfx::Point& screen_loc,
                            const std::set<HWND>& ignore)
       : BaseWindowFinder(ignore),
-        screen_loc_(screen_loc),
         result_(NULL) {
+    screen_loc_ = gfx::win::DIPToScreenPoint(screen_loc);
     EnumThreadWindows(GetCurrentThreadId(), WindowCallbackProc, as_lparam());
   }
 
-  // Position of the mouse.
+  // Position of the mouse in pixel coordinates.
   gfx::Point screen_loc_;
 
   // The resulting window. This is initially null but set to true in

ui/app_list/views/apps_grid_view.cc

@@ -46,6 +46,7 @@
 #include "ui/base/dragdrop/drop_target_win.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/dragdrop/os_exchange_data_provider_win.h"
+#include "ui/gfx/win/dpi.h"
 #endif
 
 namespace app_list {
@@ -294,6 +295,7 @@ class SynchronousDrag : public ui::DragSourceWin {
     GetCursorPos(&p);
     ScreenToClient(GetGridViewHWND(), &p);
     gfx::Point grid_view_pt(p.x, p.y);
+    grid_view_pt = gfx::win::ScreenToDIPPoint(grid_view_pt);
     views::View::ConvertPointFromWidget(grid_view_, &grid_view_pt);
     return grid_view_pt;
   }

ui/gfx/screen_win.cc

@@ -65,7 +65,8 @@ bool ScreenWin::IsDIPEnabled() {
 gfx::Point ScreenWin::GetCursorScreenPoint() {
   POINT pt;
   GetCursorPos(&pt);
-  return gfx::Point(pt);
+  gfx::Point cursor_pos_pixels(pt);
+  return gfx::win::ScreenToDIPPoint(cursor_pos_pixels);
 }
 
 gfx::NativeWindow ScreenWin::GetWindowUnderCursor() {