Merge #6969 #6970

6969:  GeckoView update (beta) (20200513-141004) r=Amejia481 a=MickeyMoz



6970:  GeckoView update (nightly) (20200513-141104) r=Amejia481 a=MickeyMoz
Co-authored-by: MickeyMoz <sebastian@mozilla.com>

buildSrc/src/main/java/Gecko.kt

@@ -6,12 +6,12 @@ internal object GeckoVersions {
     /**
      * GeckoView Nightly Version.
      */
-    const val nightly_version = "78.0.20200512093421"
+    const val nightly_version = "78.0.20200513094918"
 
     /**
      * GeckoView Beta Version.
      */
-    const val beta_version = "77.0.20200511090718"
+    const val beta_version = "77.0.20200512163137"
 
     /**
      * GeckoView Release Version.

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

@@ -58,6 +58,7 @@ The following metrics are added to the ping:
 | gfx.status.headless |[boolean](https://mozilla.github.io/glean/book/user/metrics/boolean.html) |Boolean indicated whether graphics is running in headless (no display) mode  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1594145#c4)||2021-02-01 |
 | gfx.status.sceneswap_time |[timing_distribution](https://mozilla.github.io/glean/book/user/metrics/timing_distribution.html) |The time taken to do a webrender scene swap. This is book-keeping that APZ must perform once webrender has built a new scene.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1584109#c1)||never |
 | gfx.webrender.scenebuild_time |[timing_distribution](https://mozilla.github.io/glean/book/user/metrics/timing_distribution.html) |The time taken to build a webrender scene. This occurs each time webrender receives a new display list. This additionally includes blob rasterization time.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1584109#c1)||never |
+| javascript.gc.total_time |[timing_distribution](https://mozilla.github.io/glean/book/user/metrics/timing_distribution.html) |The total time taken by a collection.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1636419#c8)||never |
 | network.cache_hit_time |[timing_distribution](https://mozilla.github.io/glean/book/user/metrics/timing_distribution.html) |Time to open existing cache entry file.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1580077#c10)||never |
 | network.dns_end |[timing_distribution](https://mozilla.github.io/glean/book/user/metrics/timing_distribution.html) |In the HTTP page channel, time from the DNS request being issued to the response.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1580077#c10)||never |
 | network.dns_start |[timing_distribution](https://mozilla.github.io/glean/book/user/metrics/timing_distribution.html) |In the HTTP page channel, time from connection open to the DNS request being issued.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1580077#c10)||never |