Implement WebContentsViewChildFrame::TakeFocus.

third_party/WebKit/Source/core/page/FocusController.cpp

Index: third_party/WebKit/Source/core/page/FocusController.cpp
diff --git a/third_party/WebKit/Source/core/page/FocusController.cpp b/third_party/WebKit/Source/core/page/FocusController.cpp
index e9723e85639f74c9dd7331209e829670966c32b4..03cd7e02be73f0350f8876180fa3275ecb854315 100644
--- a/third_party/WebKit/Source/core/page/FocusController.cpp
+++ b/third_party/WebKit/Source/core/page/FocusController.cpp
@@ -874,7 +874,9 @@ void FocusController::setFocused(bool focused) {
   if (!m_isFocused && focusedOrMainFrame()->isLocalFrame())
     toLocalFrame(focusedOrMainFrame())->eventHandler().stopAutoscroll();
 
-  if (!m_focusedFrame)
+  // Do not set a focused frame when being unfocsed. This might reset focus to

[alexmos, 2016/11/28 23:52:24]

nits: 
s/unfocsed/unfocused/
s/reset focus/reset m_isFocused/  (this is what you meant, right?)

+  // true.
+  if (!m_focusedFrame && m_isFocused)
     setFocusedFrame(m_page->mainFrame());
 
   // setFocusedFrame above might reject to update m_focusedFrame, or