UIDevTools: Test pinned and hovered element calculation

The distance calculation was broken due to pinned element and
hovered element used different coordinates. r91bef92 also fixed
this issue. This CL refactored the function name to make the
coordinates used clearer, and also added unit test to prevent
future breakage.

BUG=899001

Change-Id: Ic1e2e577eb085a82f5ea32f608312335d6befd42
Reviewed-on: https://chromium-review.googlesource.com/c/1372551
Reviewed-by: Leonard Grey <[email protected]>
Commit-Queue: Wei Li <[email protected]>
Cr-Commit-Position: refs/heads/master@{#615684}
diff --git a/components/ui_devtools/root_element.cc b/components/ui_devtools/root_element.cc
index 1a41288..5b508aa 100644
--- a/components/ui_devtools/root_element.cc
+++ b/components/ui_devtools/root_element.cc
@@ -41,8 +41,8 @@
   return nullptr;
 }
 
-std::pair<gfx::NativeWindow, gfx::Rect> RootElement::GetNodeWindowAndBounds()
-    const {
+std::pair<gfx::NativeWindow, gfx::Rect>
+RootElement::GetNodeWindowAndScreenBounds() const {
   NOTREACHED();
   return {};
 }