Fix race conditions in window snapshot code.

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index abfa452135ac776a9e2766090d9d65a3f0c6315c..efed8242679f914cfc15af979533c18536a0016d 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -23,6 +23,7 @@
 #include "base/metrics/histogram.h"
 #include "base/path_service.h"
 #include "base/process/kill.h"
+#include "base/process/process.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
@@ -194,6 +195,7 @@
 #include "third_party/WebKit/public/web/WebView.h"
 #include "third_party/WebKit/public/web/WebWindowFeatures.h"
 #include "third_party/WebKit/public/web/default/WebRenderTheme.h"
+#include "ui/base/latency_info.h"
 #include "ui/base/ui_base_switches_util.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/point.h"
@@ -2253,7 +2255,19 @@ bool RenderViewImpl::SendAndRunNestedMessageLoop(IPC::SyncMessage* message) {
 void RenderViewImpl::GetWindowSnapshot(const WindowSnapshotCallback& callback) {
   int id = next_snapshot_id_++;
   pending_snapshots_.insert(std::make_pair(id, callback));
-  Send(new ViewHostMsg_GetWindowSnapshot(routing_id_, id));
+  ui::LatencyInfo latency_info;
+  latency_info.AddLatencyNumber(ui::WINDOW_SNAPSHOT_FRAME_NUMBER_COMPONENT,
+                                GetLatencyComponentId(),
+                                id);
+  LOG(INFO) << "RenderViewImpl::GetWindowSnapshot: id = " << id << "  process id = " << (int) base::Process::Current().pid() << "  process handle = " << (int) base::GetCurrentProcessHandle() << "  routing id = " << GetRoutingID() << " latency_component_id: " << GetLatencyComponentId();
+  if (RenderWidgetCompositor* rwc = compositor()) {
+    LOG(INFO) << "  composited path";
+    rwc->SetLatencyInfo(latency_info);
+  } else {
+    LOG(INFO) << "  non-composited path";
+    latency_info_.MergeWith(latency_info);
+  }
+  ScheduleCompositeWithForcedRedraw();
 }
 
 void RenderViewImpl::OnWindowSnapshotCompleted(const int snapshot_id,
@@ -2741,6 +2755,12 @@ gfx::RectF RenderViewImpl::ClientRectToPhysicalWindowRect(
   return window_rect;
 }
 
+int64 RenderViewImpl::GetLatencyComponentId() {
+  // Note: this must match the logic in RenderWidgetHostImpl.
+  return GetRoutingID() | (static_cast<int64>(
+      RenderThreadImpl::current()->renderer_process_id()) << 32);
+}
+
 void RenderViewImpl::StartNavStateSyncTimerIfNecessary() {
   // No need to update state if no page has committed yet.
   if (page_id_ == -1)