[DevTools] Force page redraw when enabling screencast.

content/browser/devtools/renderer_overrides_handler.cc

 // Copyright (c) 2013 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/browser/devtools/renderer_overrides_handler.h"
 
 #include <map>
 #include <string>
 
 #include "base/barrier_closure.h"
@@ skipping 72 matching lines @@
 
   params->GetDouble(
       devtools::Input::emulateTouchFromMouseEvent::kParamTimestamp,
       &event->timeStampSeconds);
 }
 
 }  // namespace
 
 RendererOverridesHandler::RendererOverridesHandler(DevToolsAgentHost* agent)
     : agent_(agent),
+      has_last_compositor_frame_metadata_(false),
       capture_retry_count_(0),
       weak_factory_(this) {
   RegisterCommandHandler(
       devtools::DOM::setFileInputFiles::kName,
       base::Bind(
           &RendererOverridesHandler::GrantPermissionsForSetFileInputFiles,
           base::Unretained(this)));
   RegisterCommandHandler(
       devtools::Network::clearBrowserCache::kName,
       base::Bind(
@@ skipping 81 matching lines @@
   RenderViewHostImpl* host = static_cast<RenderViewHostImpl*>(
       agent_->GetRenderViewHost());
   if (screencast_command_ && host)
     host->SetTouchEventEmulationEnabled(false, false);
   screencast_command_ = NULL;
 }
 
 void RendererOverridesHandler::OnSwapCompositorFrame(
     const cc::CompositorFrameMetadata& frame_metadata) {
   last_compositor_frame_metadata_ = frame_metadata;
+  has_last_compositor_frame_metadata_ = true;
 
   if (screencast_command_)
     InnerSwapCompositorFrame();
 }
 
 void RendererOverridesHandler::OnVisibilityChanged(bool visible) {
   if (!screencast_command_)
     return;
   NotifyScreencastVisibility(visible);
 }
@@ skipping 330 matching lines @@
 
 scoped_refptr<DevToolsProtocol::Response>
 RendererOverridesHandler::PageStartScreencast(
     scoped_refptr<DevToolsProtocol::Command> command) {
   screencast_command_ = command;
   RenderViewHostImpl* host = static_cast<RenderViewHostImpl*>(
       agent_->GetRenderViewHost());
   host->SetTouchEventEmulationEnabled(true, true);
   bool visible = !host->is_hidden();
   NotifyScreencastVisibility(visible);
-  if (visible)
-    InnerSwapCompositorFrame();
+  if (visible) {
+    if (has_last_compositor_frame_metadata_)
+      InnerSwapCompositorFrame();
+    else
+      host->Send(new ViewMsg_ForceRedraw(host->GetRoutingID(), 0));
+  }
   return command->SuccessResponse(NULL);
 }
 
 scoped_refptr<DevToolsProtocol::Response>
 RendererOverridesHandler::PageStopScreencast(
     scoped_refptr<DevToolsProtocol::Command> command) {
   last_frame_time_ = base::TimeTicks();
   screencast_command_ = NULL;
   RenderViewHostImpl* host = static_cast<RenderViewHostImpl*>(
       agent_->GetRenderViewHost());
@@ skipping 523 matching lines @@
       return NULL;
     }
     event.data.pinchUpdate.scale = static_cast<float>(scale);
   }
 
   host->ForwardGestureEvent(event);
   return command->SuccessResponse(NULL);
 }
 
 }  // namespace content