Timeline: show white overlay till page being reloaded paints

third_party/WebKit/Source/web/WebDevToolsAgentImpl.cpp

Index: third_party/WebKit/Source/web/WebDevToolsAgentImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebDevToolsAgentImpl.cpp b/third_party/WebKit/Source/web/WebDevToolsAgentImpl.cpp
index 087fe335b8344806be73f37c313371bab207c1e4..c06af84990cd9e8ea8fd207a79112542cd5034eb 100644
--- a/third_party/WebKit/Source/web/WebDevToolsAgentImpl.cpp
+++ b/third_party/WebKit/Source/web/WebDevToolsAgentImpl.cpp
@@ -323,8 +323,9 @@ WebDevToolsAgentImpl::WebDevToolsAgentImpl(
     , m_networkAgent(nullptr)
     , m_layerTreeAgent(nullptr)
     , m_tracingAgent(nullptr)
-    , m_includeViewAgents(includeViewAgents)
     , m_layerTreeId(0)
+    , m_includeViewAgents(includeViewAgents)
+    , m_tracingActive(false)
 {
     DCHECK(isMainThread());
     DCHECK(m_webLocalFrameImpl->frame());
@@ -521,6 +522,12 @@ void WebDevToolsAgentImpl::didRemovePageOverlay(const GraphicsLayer* layer)
         m_layerTreeAgent->didRemovePageOverlay(layer);
 }
 
+void WebDevToolsAgentImpl::rootLayerCleared()
+{
+    if (m_overlay)
+        m_overlay->maybeClearReloadingBlanket();
+}
+
 void WebDevToolsAgentImpl::layerTreeViewChanged(WebLayerTreeView* layerTreeView)
 {
     m_layerTreeId = layerTreeView ? layerTreeView->layerTreeId() : 0;
@@ -532,12 +539,20 @@ void WebDevToolsAgentImpl::enableTracing(const String& categoryFilter)
 {
     if (m_client)
         m_client->enableTracing(categoryFilter);
+    m_tracingActive = true;
 }
 
 void WebDevToolsAgentImpl::disableTracing()
 {
     if (m_client)
         m_client->disableTracing();
+    m_tracingActive = false;
+}
+
+void WebDevToolsAgentImpl::willReloadPage()
+{
+    if (m_overlay && m_tracingActive)
+        m_overlay->showReloadingBlanket();
 }
 
 void WebDevToolsAgentImpl::setCPUThrottlingRate(double rate)