fix broken windows build

browser.app_panel_browser_frame_view.obj : error LNK2001: unresolved external symbol "public: virtual int __thiscall AppPanelBrowserFrameView::GetThemeBackgroundXInset(void)const " (?GetThemeBackgroundXInset@AppPanelBrowserFrameView@@UBEHXZ)
initial\chrome.dll : fatal error LNK1120: 1 unresolved externals
ninja: build stopped: subcommand failed.

See https://chromiumcodereview.appspot.com/10816004

Maybe only failing on component build? Not sure.

R=pkotwicz@chromium.org,sky@chromium.org
BUG=137090
TEST=

Review URL: https://chromiumcodereview.appspot.com/10832193

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150437 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/views/frame/app_panel_browser_frame_view.cc

@@ -107,6 +107,10 @@ AppPanelBrowserFrameView::GetTabStripInsets(bool restored) const {
   return TabStripInsets();
 }
 
+int AppPanelBrowserFrameView::GetThemeBackgroundXInset() const {
+  return 0;
+}
+
 void AppPanelBrowserFrameView::UpdateThrobber(bool running) {
   window_icon_->Update();
 }