Unreleased:
  Tracing service and probes:
    * Added more helpful error messages if the client library is used without
      having been initialized.
    * Added //tools/record_android_trace script to facilitate recording traces
      from Android devices, automating start + stop-via-ctrl+c + pull + open.
  Trace Processor:
    *
  UI:
    *


v11.0 - 2021-01-01:
  Tracing service and probes:
    * Added trace packet interceptor API for rerouting trace data into
      non-Perfetto systems.
    * Added support for printing track events to the console.
    * Added a way to observe track event tracing sessions starting and
      stopping.
  Trace Processor:
    * Added "ancestor_slice" and "experimental_ancestor_stack_profile_callsite"
      table functions to look up ancestors of CPU stack samples in profiler
      tables.
    * Added power metric reporting suspend/resume time periods.
  UI:
    * Fixed CPU time calculation in example queries.
    * Added tracks to debug Android SystemUI jank.


v10.0 - 2020-12-01:
  Tracing service and probes:
    * Fixed crash of tracing service if a client is unresponsive on the IPC
      channel. Clients are disconnected if they don't respond to IPCs for 10s.
    * Added cmdline arguments for integration within ChromeOS system image
      (--{producer,consumer}-socket-{group,mode} for chmod-ing sockets).
    * Changed path lookup logic for traced socket. /run/perfetto/ is used if the
      directory exists, falling back on /tmp/ otherwise.
    * Added support for kernel frame symbolization to the traced_perf callstack
      sampler.
    * Added support for resolving ftrace event arguments that require
      symbolization against printk_format.
  Trace Processor:
    * Added .read command to inject a SQL query file, similar to the -q cmdline.
    * Added trace-based metrics to root cause jank in Android System UI.
    * Added symbolization support for ELF files on Windows for heap and
      callstack profilers.
    * Added support for symbolizing names of workqueue ftrace events.
    * Improved Android startup metric with activity restart time.
  UI:
    * Added support for navigating flows with Ctrl+[ / Ctr+].
    * Improved query result panel, moved to the bottom group allowing
      simultaneous query result and timeline views.
    * Fixed data corruption when recording traces via the WebUSB-based Record
      page in the UI.


v9.0 - 2020-11-01:
  Tracing service and probes:
    * Added support for recording traces from a system service through the
      client API.
    * The client library now reconnects producers automatically if the
      connection to the tracing service is lost. Also fixed crashes in ongoing
      tracing sessions when a disconnect occurs.
    * Added support for dpu and g2d ftrace events.
    * Enabled commit batching and producer side patching of chunks.
    * Add support for symbolizing kernel symbols for ftrace events.
  Trace Processor:
    * Fixed type affinity of string columns.
  UI:
    * Added initial support for running metrics from the UI.
    * Added support for displaying all flows when a slice or area is selected.
    * Highlight nodes that match the 'focus' string in the flamegraph.
    * Added search within slice args.
    * Fixed details panel height and moved query panel into details panel.
    * Enabled re-sharing of postMessage traces by echoing back the original URL.
    * Improved record page error messages.


v8.0 - 2020-10-01:
  Tracing service and probes:
    * Added API for querying registered data sources and their capabilities.
    * Added support for profiling heap allocations on Linux via LD_PRELOAD.
    * Fixed possible race when initializing the consumer library.
    * Fixed subtle bugs on systems with 16KB system pages.
  Trace Processor:
    * Added a table which lists available metrics.
    * Added Python bindings on PyPi in the 'perfetto' package.
    * Added support for running trace_processor_shell on Android.
    * Added per-process metrics for GPU memory usage.
    * Added support for exporting flow events to JSON.
    * Added dynamic tables for navigating between slices of flows.
  UI:
    * Changed time marking: horizontal selection doesn't gray out anymore,
      pressing 'm' marks the range.
    * Added initial support for displaying flow event arrows.
    * Improved ordering of all thread tracks under process grouping.
    * Fixed UI crashes due to metric errors
    * Fixed selection of thread state slices.


v7.0 - 2020-09-01:
  Tracing service and probes:
    * Added auto-reconnection to the SDK. Tracing::Initialize() now retries in
      the background, instead of failing, if the tracing service is unrechable.
    * Added support for recording cpuhp (CPU hotplug) ftrace events.
    * Fixed heap profiling unwinding on multi-ABI systems.
    * Fixed reporting of live objects in the native heap profiler when using
      --dump-at-max.
    * Fixed crash when writing trace events with field nesting level > 10.
  Trace Processor:
    * Added Python bindings, see
      https://perfetto.dev/docs/analysis/trace-processor#python-api .
    * Added ingestion for Chrome instant events and Chrome flow events.
    * Added ingestion for Android GPU memory events and sched_blocked_reason.
    * Added WebView power metric.
    * Added support for WSL1 where Async I/O is not available.
    * Improved detection of Android suspend/resume events.
  UI:
    * Added GPU memory recording controls and ingestion code. Requires a recent
      Android 12+ kernel.
    * Added details panel for flow events, showed when the user selects a slice
      involved in a flow (arrows in the UI are still being worked on).
    * Added instant events rendering.
    * Added Google Analytics.
    * Fixed I/O thread-states in 4.14 kernels to deal with the removal of
      wake-kill using sched_blocked_reason.
    * Fixed "Perfetto UI started debugging this browser" showing when opening
      the UI and the Chrome extension is installed.
  Misc:
    * Update language to comply with Android's inclusive language guidance.


v6.0 - 2020-08-01:
  Tracing service and probes:
    * Added ftrace thermal events.
    * Added support for custom allocators to the heap profiler. Allows
      developers to report memory allocations that are not done through malloc.
    * Added detailed timestamping of key tracing session events.
    * Added support for building tracing services on CrOS (system-wide tracing).
    * Fixed filtering out of stale ftrace data that predates the beginning of
      the tracing session.
  Trace Processor:
    * Improved profile symbolizer. PERFETTO_SYMBOLIZER_MODE=index discovers
      symbol files by build id rather than name.
    * Added screen-state Android metrics.
  UI:
    * Added 'Info and stats' page to debug data losses and trace stats.
    * Added full cmdline to process detail panel.
    * Improved performance of async tracks using quantized queries.
    * Improved performance of counter and slice tracks for long traces by
      pre-caching quantized track data.
    * Improved actionablility of crash dialog when the Wasm module OOMs.


v5.0 - 2020-07-01:
  Tracing service and probes:
    * Added gpu_mem_total ftrace event.
    * Added TrustZone (scm start/end) event.
    * Added protos for GPU memory tracking and updated render stages proto.
    * Added time_in_state probe for Android (CPU time broken down by frequency).

  Trace Processor:
    * Added ingestion of IRQ and SoftIRQ events.
    * Added ingestion of workqueue events. KAddr symbolization still missing.
    * Added ingestion of voltage regulators and board clock change events.
    * Added ingestion of new ION ion_buffer_create/destroy events.
    * Added ingestion of TrustZone (scm start/end) events.
    * Added SurfaceFlinger derived events (tracking of missed frames).
    * Changed parsing of scheduler task state on 4.14 kernels.
    * Changed importing of Java heap graphs: allow partial dumps.
    * Improved performance of the SQL query engine.

  UI:
    * Added dedicated query page for custom SQL queries.
    * Added navigation links for Binder slices.
    * Removed overview summary mode when zoomed out.
    * Fixed recording page when targeting Android P.
    * Improved slice pan/zoom performance by quantizing.