Move plugin placeholder style to CSS, and allow it to bypass main world CSP.

Source/core/html/shadow/PluginPlaceholderElement.cpp

 // Copyright 2014 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 "config.h"
 #include "core/html/shadow/PluginPlaceholderElement.h"
 
 #include "bindings/core/v8/V8PluginPlaceholderElement.h"
 #include "core/dom/Document.h"
+#include "core/html/HTMLStyleElement.h"
+#include "public/platform/Platform.h"
 #include "wtf/Assertions.h"
+#include "wtf/text/WTFString.h"
 
 namespace blink {
 
 PluginPlaceholderElement::PluginPlaceholderElement(Document& document)
     : HTMLDivElement(document)
 {
     ScriptWrappable::init(this);
 }
 
 PassRefPtrWillBeRawPtr<PluginPlaceholderElement> PluginPlaceholderElement::create(Document& document)
 {
     RefPtrWillBeRawPtr<PluginPlaceholderElement> element = adoptRefWillBeNoop(new PluginPlaceholderElement(document));
     bool success = V8PluginPlaceholderElement::PrivateScript::createCallbackMethod(document.frame(), element.get());
     ASSERT_UNUSED(success, success);
     return element.release();
 }
 
 void PluginPlaceholderElement::setMessage(const String& htmlMessage)
 {
     bool success = V8PluginPlaceholderElement::PrivateScript::messageAttributeSetter(document().frame(), this, htmlMessage);
     ASSERT_UNUSED(success, success);
 }
 
+PassRefPtrWillBeRawPtr<HTMLStyleElement> PluginPlaceholderElement::createStyleElement()
+{
+    const WebData& styleData = Platform::current()->loadResource("PluginPlaceholderElement.css");
+    ASSERT(!styleData.isEmpty());
+    String styleSource(styleData.data(), styleData.size());
+    RefPtrWillBeRawPtr<HTMLStyleElement> styleElement = HTMLStyleElement::create(document(), false);
+    styleElement->setTextContent(styleSource);
+    styleElement->whitelistSource(styleSource);
+    return styleElement.release();
+}
+
 } // namespace blink