Merge #4801 #4802

4801:  GeckoView update (nightly) (20191020-141037) r=pocmo a=MickeyMoz



4802:  Docs update (20191021-121133) [ci skip] r=pocmo a=MickeyMoz
Co-authored-by: MickeyMoz <sebastian@mozilla.com>

buildSrc/src/main/java/Gecko.kt

@@ -6,7 +6,7 @@ internal object GeckoVersions {
     /**
      * GeckoView Nightly Version.
      */
-    const val nightly_version = "71.0.20191018095340"
+    const val nightly_version = "71.0.20191020094538"
 
     /**
      * GeckoView Beta Version.

components/browser/engine-gecko-nightly/docs/metrics.md

@@ -27,7 +27,7 @@ The following metrics are added to the ping:
 | gfx.composite_time |[timing_distribution](https://mozilla.github.io/glean/book/user/metrics/timing_distribution.html) |The time taken to composite a frame. On non-webrender this is the time taken in `CompositorBridgeParent::CompositeToTarget()`. On webrender, this is the time taken from the start of `WebRenderBridgeParent::CompositeToTarget()`, until the render thread has rendered the frame (in `RenderThread::HandleFrameOneDoc()`).  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1580129#c7)||never |
 | gfx.content.frame_time.from_paint |[custom_distribution](https://mozilla.github.io/glean/book/user/metrics/custom_distribution.html) |The time, in percentage of a vsync interval, spent from beginning a paint in the content process until that frame is presented in the compositor.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1584109#c1)||never |
 | gfx.content.frame_time.from_vsync |[custom_distribution](https://mozilla.github.io/glean/book/user/metrics/custom_distribution.html) |The time, in percentage of a vsync interval, spent from the vsync that started a paint in the content process until that frame is presented in the compositor.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1584109#c1)||never |
-| gfx.content.frame_time.reason |[labeled_counter](https://mozilla.github.io/glean/book/user/metrics/labeled_counters.html) |The reason that `gfx.content.frame_time.from_paint` recorded a slow (>200ms) result, if any.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1584109#c1)|<ul><li>on_time</li><li>no_vsync_no_id</li><li>missed_composite</li><li>slow_composite</li><li>missed_composite_long</li><li>missed_composite_low</li><li>missed_composite_mid</li><li>no_vsync</li></ul>|never |
+| gfx.content.frame_time.reason |[labeled_counter](https://mozilla.github.io/glean/book/user/metrics/labeled_counters.html) |The reason that `gfx.content.frame_time.from_paint` recorded a slow (>200ms) result, if any.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1584109#c1)|<ul><li>slow_composite</li><li>no_vsync_no_id</li><li>missed_composite_long</li><li>missed_composite_mid</li><li>no_vsync</li><li>missed_composite</li><li>on_time</li><li>missed_composite_low</li></ul>|never |
 | gfx.content.frame_time.with_svg |[custom_distribution](https://mozilla.github.io/glean/book/user/metrics/custom_distribution.html) |The time, in percentage of a vsync interval, spent from beginning a paint in the content process until that frame is presented in the compositor, for frames that contained an SVG to be drawn by webrender.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1584109#c1)||never |
 | gfx.content.frame_time.without_resource_upload |[custom_distribution](https://mozilla.github.io/glean/book/user/metrics/custom_distribution.html) |The time, in percentage of a vsync interval, spent from beginning a paint in the content process until that frame is presented in the compositor by webrender, excluding time spent uploading resources.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1584109#c1)||never |
 | gfx.content.frame_time.without_upload |[custom_distribution](https://mozilla.github.io/glean/book/user/metrics/custom_distribution.html) |The time, in percentage of a vsync interval, spent from beginning a paint in the content process until that frame is presented in the compositor by webrender, excluding time spent uploading any content.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1584109#c1)||never |