Don't allow dirtying layout during paint of a plugin placeholder.

components/plugins/renderer/webview_plugin.cc

Index: components/plugins/renderer/webview_plugin.cc
diff --git a/components/plugins/renderer/webview_plugin.cc b/components/plugins/renderer/webview_plugin.cc
index 995ff09bcff0f2cb0ae812f3dd4bd43979a69c86..3186391bdf6bd479d80aca509ec9ab6df5ebf070 100644
--- a/components/plugins/renderer/webview_plugin.cc
+++ b/components/plugins/renderer/webview_plugin.cc
@@ -55,7 +55,8 @@ WebViewPlugin::WebViewPlugin(content::RenderView* render_view,
       container_(nullptr),
       web_view_(WebView::create(this)),
       finished_loading_(false),
-      focused_(false) {
+      focused_(false),
+      is_painting_(false) {
   // ApplyWebPreferences before making a WebLocalFrame so that the frame sees a
   // consistent view of our preferences.
   content::RenderView::ApplyWebPreferences(preferences, web_view_);
@@ -172,6 +173,8 @@ void WebViewPlugin::paint(WebCanvas* canvas, const WebRect& rect) {
   if (paint_rect.IsEmpty())
     return;
 
+  is_painting_ = true;

[tommycli, 2016/02/08 22:20:43]

Seems like this should use base::AutoReset

[chrishtr, 2016/02/08 22:43:38]

Done.

+
   paint_rect.Offset(-rect_.x(), -rect_.y());
 
   canvas->save();
@@ -186,6 +189,7 @@ void WebViewPlugin::paint(WebCanvas* canvas, const WebRect& rect) {
   web_view_->paint(canvas, paint_rect);
 
   canvas->restore();
+  is_painting_ = false;
 }
 
 // Coordinates are relative to the containing window.
@@ -288,7 +292,7 @@ void WebViewPlugin::didChangeCursor(const WebCursorInfo& cursor) {
 }
 
 void WebViewPlugin::scheduleAnimation() {
-  if (container_)
+  if (container_ && !is_painting_)

[tommycli, 2016/02/08 22:20:43]

If this should not happen anyways, shouldn't this be a CHECK?

[chrishtr, 2016/02/08 22:43:39]

Added DCHECK plus defensive logic.

     container_->setNeedsLayout();
 }