Fix cursor lifetime and turn on mus browser tests on the bots.

Previous attempts at trying to fix the cursor lifetime issue assumed
that it was related to ownership while passing refcounted objects across
thread boundaries. This patch, instead, frees the passed cursor
depending on how it was created.

Bug: 800219
Change-Id: Iaee3748716b155dfd180923712838870cfb21c47
Reviewed-on: https://chromium-review.googlesource.com/864833Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Elliot Glaysher <erg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531711}

services/ui/ws/threaded_image_cursors.cc

@@ -98,9 +98,10 @@ void SetCustomCursorOnResourceThread(
     // |platform_window| is owned by the UI Service thread, so setting the
     // cursor on it also needs to happen on that thread.
     ui_service_task_runner_->PostTask(
-        FROM_HERE, base::Bind(&ThreadedImageCursors::SetCursorOnPlatformWindow,
-                              threaded_image_cursors_weak_ptr, platform_cursor,
-                              platform_window));
+        FROM_HERE,
+        base::Bind(&ThreadedImageCursors::SetCursorOnPlatformWindowAndUnref,
+                   threaded_image_cursors_weak_ptr, platform_cursor,
+                   platform_window));
   }
 }
 #endif  // defined(USE_OZONE)
@@ -207,5 +208,25 @@ void ThreadedImageCursors::SetCursorOnPlatformWindow(
   platform_window->SetCursor(platform_cursor);
 }
 
+#if defined(USE_OZONE)
+void ThreadedImageCursors::SetCursorOnPlatformWindowAndUnref(
+    ui::PlatformCursor platform_cursor,
+    ui::PlatformWindow* platform_window) {
+  SetCursorOnPlatformWindow(platform_cursor, platform_window);
+
+  // The PlatformCursor returned by CreateAnimatedCursor() has a single
+  // refcount which is owned by the caller. If we were returned a valid
+  // |platform_cursor|, we must unref it here. All implementations of
+  // PlatformWindow::SetCursor() which need to keep the PlatformCursor have
+  // increased the refcount for their self.
+  //
+  // Note: Cursors returned by SetPlatformCursor() do not return custom bitmap
+  // cursors. The refcount of such a cursor is owned by the caller and
+  // shouldn't be refed/unrefed by the caller.
+  if (platform_cursor)
+    ui::CursorFactoryOzone::GetInstance()->UnrefImageCursor(platform_cursor);
+}
+#endif
+
 }  // namespace ws
 }  // namespace ui

services/ui/ws/threaded_image_cursors.h

@@ -66,6 +66,10 @@ class ThreadedImageCursors {
   // Helper method. Sets |platform_cursor| on the |platform_window|.
   void SetCursorOnPlatformWindow(ui::PlatformCursor platform_cursor,
                                  ui::PlatformWindow* platform_window);
+#if defined(USE_OZONE)
+  void SetCursorOnPlatformWindowAndUnref(ui::PlatformCursor platform_cursor,
+                                         ui::PlatformWindow* platform_window);
+#endif
 
  private:
   // The object used for performing the actual cursor operations.

testing/buildbot/chromium.memory.json

@@ -946,6 +946,19 @@
         },
         "test": "browser_tests"
       },
+      {
+        "args": [
+          "--mus",
+          "--ozone-platform=headless",
+          "--override-use-software-gl-for-tests"
+        ],
+        "name": "mus_browser_tests",
+        "swarming": {
+          "can_use_on_swarming_builders": true,
+          "shards": 10
+        },
+        "test": "browser_tests"
+      },
       {
         "swarming": {
           "can_use_on_swarming_builders": true

testing/buildbot/test_suite_exceptions.pyl

@@ -2537,12 +2537,6 @@
       },
     },
   },
-  'mus_browser_tests': {
-    'remove_from': [
-      # chromium.memory
-      'Linux Chromium OS ASan LSan Tests (1)',
-    ]
-  },
   'nacl_helper_nonsfi_unittests': {
     'remove_from': [
       # chromium.clang