ash: Fix WorkspaceWindowResizerTest.ResizeHistogram

- WorkspaceWindowResizer::CompleteDrag() does not necessarily
  trigger a new compositor frame. As a result, the wait for the
  next frame could time out. This CL fixes the issue by explicitly
  marking a damaged rect to ensure a new frame is produced;
- Fix ui::WaitForNextFrameToBePresented use-after-free by using
  a CancelableCallback as the frame presented callback so that
  local var |runloop| is not accessed when it times out;

Bug: 1047657
Change-Id: I6e7ac27f14d92adf3c9d1535fec62e32e3964f2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2036369Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738176}

ash/wm/workspace/workspace_window_resizer_unittest.cc

@@ -1905,7 +1905,7 @@ TEST_F(WorkspaceWindowResizerTest, TouchResizeToEdge_BOTTOM) {
             touch_resize_window_->bounds().ToString());
 }
 
-TEST_F(WorkspaceWindowResizerTest, DISABLED_ResizeHistogram) {
+TEST_F(WorkspaceWindowResizerTest, ResizeHistogram) {
   base::HistogramTester histograms;
   window_->SetBounds(gfx::Rect(20, 30, 400, 60));
   std::unique_ptr<WindowResizer> resizer(
@@ -1920,6 +1920,12 @@ TEST_F(WorkspaceWindowResizerTest, DISABLED_ResizeHistogram) {
 
   // Completing the drag should not generate another histogram.
   resizer->CompleteDrag();
+
+  // Ensures a compositor frame will be generated. Otherwise,
+  // ui::WaitForNextFrameToBePresented below could time out.
+  // See https://crbug.com/1047657.
+  window_->GetHost()->compositor()->ScheduleRedrawRect(gfx::Rect(0, 0, 1, 1));
+
   ui::WaitForNextFrameToBePresented(window_->GetHost()->compositor());
   histograms.ExpectTotalCount("Ash.InteractiveWindowResize.TimeToPresent", 1);
 }

ui/compositor/test/test_utils.cc

@@ -4,6 +4,7 @@
 
 #include "ui/compositor/test/test_utils.h"
 
+#include "base/cancelable_callback.h"
 #include "base/run_loop.h"
 #include "base/test/bind_test_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -50,10 +51,13 @@ void CheckApproximatelyEqual(const gfx::RoundedCornersF& lhs,
 
 void WaitForNextFrameToBePresented(ui::Compositor* compositor) {
   base::RunLoop runloop;
-  compositor->RequestPresentationTimeForNextFrame(base::BindLambdaForTesting(
-      [&runloop](const gfx::PresentationFeedback& feedback) {
-        runloop.Quit();
-      }));
+  base::CancelableOnceCallback<void(const gfx::PresentationFeedback&)>
+      cancelable_callback(base::BindLambdaForTesting(
+          [&runloop](const gfx::PresentationFeedback& feedback) {
+            runloop.Quit();
+          }));
+  compositor->RequestPresentationTimeForNextFrame(
+      cancelable_callback.callback());
   runloop.Run();
 }