Use contents size for android_webview layout.

android_webview/browser/renderer_host/aw_render_view_host_ext.cc

Index: android_webview/browser/renderer_host/aw_render_view_host_ext.cc
diff --git a/android_webview/browser/renderer_host/aw_render_view_host_ext.cc b/android_webview/browser/renderer_host/aw_render_view_host_ext.cc
index 78d6cf4b4efb3361416185bc6e953582162e04fe..f5ab968248e2ab89ba0d126500a9ca913fc052a5 100644
--- a/android_webview/browser/renderer_host/aw_render_view_host_ext.cc
+++ b/android_webview/browser/renderer_host/aw_render_view_host_ext.cc
@@ -134,6 +134,8 @@ bool AwRenderViewHostExt::OnMessageReceived(const IPC::Message& message) {
                         OnUpdateHitTestData)
     IPC_MESSAGE_HANDLER(AwViewHostMsg_PageScaleFactorChanged,
                         OnPageScaleFactorChanged)
+    IPC_MESSAGE_HANDLER(AwViewHostMsg_OnContentsSizeChanged,
+                        OnContentsSizeChanged)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
@@ -164,4 +166,9 @@ void AwRenderViewHostExt::OnPageScaleFactorChanged(float page_scale_factor) {
   client_->OnWebLayoutPageScaleFactorChanged(page_scale_factor);
 }
 
+void AwRenderViewHostExt::OnContentsSizeChanged(
+    const gfx::Size& contents_size) {
+  client_->OnWebLayoutContentsSizeChanged(contents_size);
+}
+
 }  // namespace android_webview