Fix the issue that webview-browser-sample crashed on Mac.

content/renderer/browser_plugin/browser_plugin.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/browser_plugin/browser_plugin.h"
 
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 33 matching lines @@
 
 BrowserPlugin::BrowserPlugin(RenderViewImpl* render_view,
                              blink::WebFrame* frame,
                              bool auto_navigate)
     : guest_instance_id_(browser_plugin::kInstanceIDNone),
       attached_(false),
       render_view_(render_view->AsWeakPtr()),
       render_view_routing_id_(render_view->GetRoutingID()),
       container_(NULL),
       paint_ack_received_(true),
-      last_device_scale_factor_(1.0f),
+      last_device_scale_factor_(GetDeviceScaleFactor()),
       sad_guest_(NULL),
       guest_crashed_(false),
       is_auto_size_state_dirty_(false),
       content_window_routing_id_(MSG_ROUTING_NONE),
       plugin_focused_(false),
       visible_(true),
       auto_navigate_(auto_navigate),
       mouse_locked_(false),
       browser_plugin_manager_(render_view->GetBrowserPluginManager()),
       embedder_frame_url_(frame->document().url()),
@@ skipping 888 matching lines @@
     const blink::WebMouseEvent& event) {
   browser_plugin_manager()->Send(
       new BrowserPluginHostMsg_HandleInputEvent(render_view_routing_id_,
                                                 guest_instance_id_,
                                                 plugin_rect_,
                                                 &event));
   return true;
 }
 
 }  // namespace content