7537 Add mock capability to PerformanceOverlayLayer (cla: yes)

7538 Allow embedders to specify AOT snapshot buffers. (cla: yes)

7539 IWYU to get SkFontMetrics (cla: yes)

7544 Keep engine alive if VC is not deallocated (cla: yes)

7545 IWYU, esp. since SkFontMetrics.h is leaving SkPaint.h (cla: yes)

7548 Remove SkColorSpaceXformCanvas, use color-managed SkSurfaces instead (cla: yes)

7549 Remove the shell build target’s dependency on the embedder library (cla: yes)

7551 Re-land “Wrap the user entrypoint function in a zone with native exception callback. (#7512)” (cla: yes)