Implemented ForceMaximizeBrowserWindowOnFirstRun policy, added unit test and browser test.

ash/shell/shell_delegate_impl.cc

Index: ash/shell/shell_delegate_impl.cc
diff --git a/ash/shell/shell_delegate_impl.cc b/ash/shell/shell_delegate_impl.cc
index dc081c6fc359aba744fdf4c1c1020099b65bc638..bd5823e93623985f60e6623922c078aeff461fe1 100644
--- a/ash/shell/shell_delegate_impl.cc
+++ b/ash/shell/shell_delegate_impl.cc
@@ -181,6 +181,10 @@ bool ShellDelegateImpl::IsMultiAccountEnabled() const {
   return false;
 }
 
+bool ShellDelegateImpl::ForceMaximizeOnFirstRun() const {
+  return false;
+}
+
 void ShellDelegateImpl::PreInit() {
 }