Selection API: Do not change focus by Selection functions.

third_party/WebKit/Source/core/editing/FrameSelection.h

Index: third_party/WebKit/Source/core/editing/FrameSelection.h
diff --git a/third_party/WebKit/Source/core/editing/FrameSelection.h b/third_party/WebKit/Source/core/editing/FrameSelection.h
index 2e8a12df037fd6b5886b930713f5009ac1964cce..4680b75833864e1f5df792f3a8e4667fb8ac5bb6 100644
--- a/third_party/WebKit/Source/core/editing/FrameSelection.h
+++ b/third_party/WebKit/Source/core/editing/FrameSelection.h
@@ -119,6 +119,8 @@ class CORE_EXPORT FrameSelection final
   // layout.
   const VisibleSelection& computeVisibleSelectionInDOMTreeDeprecated() const;
 
+  // setSelection() and setSelectedRange() functions may dispatch focus-related
+  // synchronous events unless DoNotSetFocus is specified.
   void setSelection(const SelectionInDOMTree&,
                     SetSelectionOptions = CloseTyping | ClearTypingStyle,
                     CursorAlignOnScroll = CursorAlignOnScroll::IfNeeded,
@@ -149,7 +151,10 @@ class CORE_EXPORT FrameSelection final
       TextAffinity,
       SelectionDirectionalMode = SelectionDirectionalMode::NonDirectional,
       FrameSelection::SetSelectionOptions = CloseTyping | ClearTypingStyle);
+
+  // selectAll() may dispatch focus-related synchronous events.
   void selectAll();
+
   void clear();
 
   // Call this after doing user-triggered selections to make it easy to delete
@@ -158,10 +163,15 @@ class CORE_EXPORT FrameSelection final
 
   bool contains(const LayoutPoint&);
 
+  // This function may dispatch focus-related synchronous events unless
+  // DoNotSetFocus is specified.
+  //
+  // |noFocusFlag| must be 0 or SetSelectionOptions::DoNotSetFocus.
   bool modify(EAlteration,
               SelectionDirection,
               TextGranularity,
-              EUserTriggered = NotUserTriggered);
+              EUserTriggered = NotUserTriggered,
+              SetSelectionOptions noFocusFlag = 0);
   enum VerticalDirection { DirectionUp, DirectionDown };
   bool modify(EAlteration, unsigned verticalDistance, VerticalDirection);