Discard compositor frames from unloaded web content

content/browser/renderer_host/render_widget_host_unittest.cc

Index: content/browser/renderer_host/render_widget_host_unittest.cc
diff --git a/content/browser/renderer_host/render_widget_host_unittest.cc b/content/browser/renderer_host/render_widget_host_unittest.cc
index 439ffccedb40398ae6ee560f5d6bc3cab984af69..7b74276b680d62098c1593060e633c215d77d2d1 100644
--- a/content/browser/renderer_host/render_widget_host_unittest.cc
+++ b/content/browser/renderer_host/render_widget_host_unittest.cc
@@ -1242,7 +1242,7 @@ TEST_F(RenderWidgetHostTest, NewContentRenderingTimeout) {
       base::TimeDelta::FromMicroseconds(10));
 
   // Test immediate start and stop, ensuring that the timeout doesn't fire.
-  host_->StartNewContentRenderingTimeout();
+  host_->StartNewContentRenderingTimeout(0);
   host_->OnFirstPaintAfterLoad();
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE, base::MessageLoop::QuitWhenIdleClosure(),
@@ -1254,7 +1254,7 @@ TEST_F(RenderWidgetHostTest, NewContentRenderingTimeout) {
   // Test that the timer doesn't fire if it receives a stop before
   // a start.
   host_->OnFirstPaintAfterLoad();
-  host_->StartNewContentRenderingTimeout();
+  host_->StartNewContentRenderingTimeout(0);
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE, base::MessageLoop::QuitWhenIdleClosure(),
       TimeDelta::FromMicroseconds(20));
@@ -1263,7 +1263,7 @@ TEST_F(RenderWidgetHostTest, NewContentRenderingTimeout) {
   EXPECT_FALSE(host_->new_content_rendering_timeout_fired());
 
   // Test with a long delay to ensure that it does fire this time.
-  host_->StartNewContentRenderingTimeout();
+  host_->StartNewContentRenderingTimeout(0);
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE, base::MessageLoop::QuitWhenIdleClosure(),
       TimeDelta::FromMicroseconds(20));
@@ -1271,6 +1271,39 @@ TEST_F(RenderWidgetHostTest, NewContentRenderingTimeout) {
   EXPECT_TRUE(host_->new_content_rendering_timeout_fired());
 }
 
+// This tests that a compositor frame received with a stale content source ID
+// in its metadata is properly discarded.
+TEST_F(RenderWidgetHostTest, SwapCompositorFrameWithBadSourceId) {
+  host_->StartNewContentRenderingTimeout(100);
+  host_->OnFirstPaintAfterLoad();
+
+  // First swap a frame with an invalid ID.
+  cc::CompositorFrame frame;
+  frame.metadata.content_source_id = 99;
+  host_->OnMessageReceived(ViewHostMsg_SwapCompositorFrame(
+      0, 0, frame, std::vector<IPC::Message>()));
+  EXPECT_FALSE(
+      static_cast<TestView*>(host_->GetView())->did_swap_compositor_frame());
+  static_cast<TestView*>(host_->GetView())->reset_did_swap_compositor_frame();
+
+  // Test with a valid content ID as a control.
+  frame.metadata.content_source_id = 100;
+  host_->OnMessageReceived(ViewHostMsg_SwapCompositorFrame(
+      0, 0, frame, std::vector<IPC::Message>()));
+  EXPECT_TRUE(
+      static_cast<TestView*>(host_->GetView())->did_swap_compositor_frame());
+  static_cast<TestView*>(host_->GetView())->reset_did_swap_compositor_frame();
+
+  // We also accept frames with higher content IDs, to cover the case where
+  // the browser process receives a compositor frame for a new page before
+  // the corresponding DidCommitProvisionalLoad (it's a race).
+  frame.metadata.content_source_id = 101;
+  host_->OnMessageReceived(ViewHostMsg_SwapCompositorFrame(
+      0, 0, frame, std::vector<IPC::Message>()));
+  EXPECT_TRUE(
+      static_cast<TestView*>(host_->GetView())->did_swap_compositor_frame());
+}
+
 TEST_F(RenderWidgetHostTest, TouchEmulator) {
   simulated_event_time_delta_seconds_ = 0.1;
   // Immediately ack all touches instead of sending them to the renderer.