Migrate Event API methods to Google Style.

views/controls/scrollbar/bitmap_scroll_bar.cc

Index: views/controls/scrollbar/bitmap_scroll_bar.cc
===================================================================
--- views/controls/scrollbar/bitmap_scroll_bar.cc	(revision 74326)
+++ views/controls/scrollbar/bitmap_scroll_bar.cc	(working copy)
@@ -491,13 +491,13 @@
 }
 
 bool BitmapScrollBar::OnMouseWheel(const MouseWheelEvent& event) {
-  ScrollByContentsOffset(event.GetOffset());
+  ScrollByContentsOffset(event.offset());
   return true;
 }
 
 bool BitmapScrollBar::OnKeyPressed(const KeyEvent& event) {
   ScrollAmount amount = SCROLL_NONE;
-  switch (event.GetKeyCode()) {
+  switch (event.key_code()) {
     case ui::VKEY_UP:
       if (!IsHorizontal())
         amount = SCROLL_PREV_LINE;