Revert "Pre-emptively take a snapshot when finishing an activity befo…

…re changing visibility"

This reverts commit 6dad90e.

When opening and closing activities in Settings, a significant amount of
CPU time is spent rendering and compressing JPEG screenshots, as
reported by simpleperf:

0.46%     /system/lib64/libjpeg.so                                                                                                                  encode_mcu_gather
0.37%     /system/lib64/libhwui.so                                                                                                                  neon::S32_alpha_D32_filter_DX(SkBitmapProcState const&, unsigned int const*, int, unsigned int*)
0.29%     /system/lib64/libjpeg.so                                                                                                                  jsimd_extrgbx_ycc_convert_neon
0.27%     /system/lib64/libjpeg.so                                                                                                                  jsimd_fdct_islow_neon
0.23%     /system/lib64/libjpeg.so                                                                                                                  jsimd_huff_encode_one_block_neon
0.14%     /system/lib64/libjpeg.so                                                                                                                  jsimd_quantize_neon

Call graph tracing reveals that TaskSnapshotPersister is responsible for
taking the screenshots:

0.16%     0.16%  /system/lib64/libjpeg.so                                                                                                encode_mcu_gather
       |
       -- encode_mcu_gather
          |
           --50.00%-- compress_output
                      process_data_simple_main
                      jpeg_write_scanlines
                      SkJpegEncoder::onEncodeRows(int)
                      SkJpegEncoder::Encode(SkWStream*, SkPixmap const&, SkJpegEncoder::Options const&)
                      SkEncodeImage(SkWStream*, SkPixmap const&, SkEncodedImageFormat, int)
                      android::Bitmap::compress(SkBitmap const&, android::Bitmap::JavaCompressFormat, int, SkWStream*)
                      android::Bitmap::compress(android::Bitmap::JavaCompressFormat, int, SkWStream*)
                      Bitmap_compress(_JNIEnv*, _jobject*, long, int, int, _jobject*, _jbyteArray*)
                      art_jni_trampoline
                      android.graphics.Bitmap.compress
                      com.android.server.wm.TaskSnapshotPersister$StoreWriteQueueItem.writeBuffer
                      com.android.server.wm.TaskSnapshotPersister$StoreWriteQueueItem.write
                      com.android.server.wm.TaskSnapshotPersister$1.run
                      art_quick_invoke_stub
                      art::ArtMethod::Invoke(art::Thread*, unsigned int*, unsigned int, art::JValue*, char const*)
                      art::JValue art::InvokeVirtualOrInterfaceWithJValues<art::ArtMethod*>(art::ScopedObjectAccessAlreadyRunnable const&, _jobject*, art::ArtMethod*, jvalue const*)
                      art::Thread::CreateCallback(void*)
                      __pthread_start(void*)
                      __start_thread

Manual code tracing leads to ActivityRecord as the culprit, as it takes
a screenshot every time an Activity is finished. This doesn't appear to
be critical, so revert the commit that added it in order to reduce
excess CPU usage.

Test: simpleperf record -a; verify that libjpeg-turbo no longer appears
      in top sample hits
Change-Id: Ib161679f1f3b83787f90b8ef7dcf46d246bb7c57

services/core/java/com/android/server/wm/ActivityRecord.java

@@ -347,8 +347,6 @@
 import com.android.server.wm.WindowManagerService.H;
 import com.android.server.wm.utils.InsetUtils;
 
-import com.google.android.collect.Sets;
-
 import org.xmlpull.v1.XmlPullParserException;
 
 import java.io.File;
@@ -3145,19 +3143,6 @@ private void finishActivityResults(int resultCode, Intent resultData,
                 }
                 mDisplayContent.prepareAppTransition(TRANSIT_CLOSE);
 
-                // When finishing the activity preemptively take the snapshot before the app window
-                // is marked as hidden and any configuration changes take place
-                // Note that RecentsAnimation will handle task snapshot while switching apps with
-                // the best capture timing (e.g. IME window capture),
-                // No need additional task capture while task is controlled by RecentsAnimation.
-                if (mAtmService.mWindowManager.mTaskSnapshotController != null
-                        && !task.isAnimatingByRecents()) {
-                    final ArraySet<Task> tasks = Sets.newArraySet(task);
-                    mAtmService.mWindowManager.mTaskSnapshotController.snapshotTasks(tasks);
-                    mAtmService.mWindowManager.mTaskSnapshotController
-                            .addSkipClosingAppSnapshotTasks(tasks);
-                }
-
                 // Tell window manager to prepare for this one to be removed.
                 setVisibility(false);