Convert drag event position to root frame.

Convert drag event position to root frame.

The drag event positions are in viewport's coordinates when they are passed in
blink::WebView. We then need to convert these coordinates into the root frame.
In this way, the page scale factor is properly factored into the coordination
conversion.

BUG=651626, 652789
Review-Url: https://codereview.chromium.org/2396693002
Cr-Commit-Position: refs/heads/master@{#423250}
(cherry picked from commit 3d4fa85236725f161e2870a69faaca75c4e2a67d)

 Conflicts:
	third_party/WebKit/Source/web/WebViewImpl.cpp
	third_party/WebKit/Source/web/WebViewImpl.h
	third_party/WebKit/public/web/WebView.h

Committed: https://chromium.googlesource.com/chromium/src/+/4eab7d2715b508e2893a6bd62919aa44a3c20f41

[hush (inactive), 2016-10-05 20:26:39]

Description was changed from

==========
Convert drag event position to root frame.

The drag event positions are in viewport's coordinates when they are passed in
blink::WebView. We then need to convert these coordinates into the root frame.
In this way, the page scale factor is properly factored into the coordination
conversion.

BUG=651626, 652789

Review-Url: https://codereview.chromium.org/2396693002
Cr-Commit-Position: refs/heads/master@{#423250}
(cherry picked from commit 3d4fa85236725f161e2870a69faaca75c4e2a67d)

 Conflicts:
	third_party/WebKit/Source/web/WebViewImpl.cpp
	third_party/WebKit/Source/web/WebViewImpl.h
	third_party/WebKit/public/web/WebView.h
==========

to

==========
Convert drag event position to root frame.

The drag event positions are in viewport's coordinates when they are passed in
blink::WebView. We then need to convert these coordinates into the root frame.
In this way, the page scale factor is properly factored into the coordination
conversion.

BUG=651626, 652789

Review-Url: https://codereview.chromium.org/2396693002
Cr-Commit-Position: refs/heads/master@{#423250}
(cherry picked from commit 3d4fa85236725f161e2870a69faaca75c4e2a67d)

 Conflicts:
	third_party/WebKit/Source/web/WebViewImpl.cpp
	third_party/WebKit/Source/web/WebViewImpl.h
	third_party/WebKit/public/web/WebView.h

Committed:
https://chromium.googlesource.com/chromium/src/+/4eab7d2715b508e2893a6bd62919...
==========

[hush (inactive), 2016-10-05 20:26:40]

Committed patchset #1 (id:1) manually as
4eab7d2715b508e2893a6bd62919aa44a3c20f41.