Fix title bar drag hit testing when in RTL mode

Our hit testing for the title bar window control buttons was not taking
RTL mirroring into account. This CL fixes that.
Without this CL the user was not able to drag the window in the top
right corner when in RTL mode.

Fixed: 1008371
Change-Id: Id84d381dca00ebb70931e3692fe4982df8827471
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1943491
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Auto-Submit: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720360}

chrome/browser/ui/views/frame/glass_browser_frame_view.cc

@@ -330,8 +330,8 @@ int GlassBrowserFrameView::NonClientHitTest(const gfx::Point& point) {
                                         DWMWA_CAPTION_BUTTON_BOUNDS,
                                         &button_bounds,
                                         sizeof(button_bounds)))) {
-      gfx::Rect buttons = gfx::ConvertRectToDIP(display::win::GetDPIScale(),
-                                                gfx::Rect(button_bounds));
+      gfx::Rect buttons = GetMirroredRect(gfx::ConvertRectToDIP(
+          display::win::GetDPIScale(), gfx::Rect(button_bounds)));
 
       // There is a small one-pixel strip right above the caption buttons in
       // which the resize border "peeks" through.

chrome/browser/ui/views/frame/glass_browser_frame_view_browsertest_win.cc

@@ -98,3 +98,17 @@ IN_PROC_BROWSER_TEST_F(WebAppGlassBrowserFrameViewTest, MaximizedLayout) {
   DCHECK_GT(glass_frame_view_->window_title_for_testing()->x(), 0);
   DCHECK_GT(glass_frame_view_->web_app_frame_toolbar_for_testing()->y(), 0);
 }
+
+IN_PROC_BROWSER_TEST_F(WebAppGlassBrowserFrameViewTest, RTLTopRightHitTest) {
+  base::i18n::SetRTLForTesting(true);
+  if (!InstallAndLaunchWebApp())
+    return;
+
+  static_cast<views::View*>(glass_frame_view_)->Layout();
+
+  // Avoid the top right resize corner.
+  constexpr int kInset = 10;
+  EXPECT_EQ(glass_frame_view_->NonClientHitTest(
+                gfx::Point(glass_frame_view_->width() - kInset, kInset)),
+            HTCAPTION);
+}