Compute the popup location/size correctly when use-zoom-for-dsf is enabled.

third_party/WebKit/Source/web/PopupMenuImpl.cpp

Index: third_party/WebKit/Source/web/PopupMenuImpl.cpp
diff --git a/third_party/WebKit/Source/web/PopupMenuImpl.cpp b/third_party/WebKit/Source/web/PopupMenuImpl.cpp
index fb5b708e805c7daee9cf85d58a25c2ec790db557..63b1a6620a15b9d9fd84677cfbb631491353003a 100644
--- a/third_party/WebKit/Source/web/PopupMenuImpl.cpp
+++ b/third_party/WebKit/Source/web/PopupMenuImpl.cpp
@@ -289,9 +289,11 @@ void PopupMenuImpl::writeDocument(SharedBuffer* data)
     context.finishGroupIfNecessary();
     PagePopupClient::addString("],\n", data);
 
-    float zoom = zoomFactor();
     addProperty("anchorRectInScreen", anchorRectInScreen, data);
-    addProperty("zoomFactor", zoom, data);
+    float zoom = zoomFactor();
+    IntRect inScreen = m_chromeClient->viewportToScreen(IntRect(0, 0, 100, 0));

[oshima, 2015/12/08 21:21:32]

Please let me know if you prefer to add a separate API to get the
viewport->window scale.

+    float scaleFactor = 100.f / inScreen.width();
+    addProperty("zoomFactor", zoom / scaleFactor, data);

[oshima, 2015/12/08 21:21:32]

Please let me know if you prefer to rename zoomFactor to something else (like
just scaleFactor).

     bool isRTL = !ownerStyle->isLeftToRightDirection();
     addProperty("isRTL", isRTL, data);
     addProperty("paddingStart", isRTL ? ownerElement.clientPaddingRight().toDouble() / zoom : ownerElement.clientPaddingLeft().toDouble() / zoom, data);