28973 Manual clang roll (cla: yes)

28975 made it so you can specify which adb to use for android tests (cla: yes, waiting for tree to go green)

28976 Roll Skia from f69f21e601f9 to 7bb0ff05cec5 (7 revisions) (cla: yes, waiting for tree to go green)

28977 Remove some deprecated APIs from the Android embedding (platform-android, cla: yes, waiting for tree to go green, needs tests)

28979 Roll Dart SDK from 4a4c1361ad7b to 4fa07f3ccd43 (1 revision) (cla: yes, waiting for tree to go green)

28980 [fuchsia][flatland] Fix for AwaitVsync race (cla: yes, platform-fuchsia)