Enable PictureInPictureAPI feature on Desktop.

Picture-in-Picture API is now enabled by default on Chrome OS, Linux,
Mac, and Windows. Android will come later.

Intent to ship: https://groups.google.com/a/chromium.org/d/msg/blink-dev/ibVPbqBQapU/rUZIrPPLAQAJ

Bug: 806249
Change-Id: I32fb2b491406e5592e57f64a5483bebf887ebdc0
Reviewed-on: https://chromium-review.googlesource.com/1090728Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#569186}

content/child/runtime_features.cc

@@ -51,6 +51,7 @@ static void SetRuntimeFeatureDefaultsForPlatform() {
   WebRuntimeFeatures::EnableMediaSession(true);
   WebRuntimeFeatures::EnableMediaControlsOverlayPlayButton(true);
   WebRuntimeFeatures::EnableRemotePlaybackBackend(true);
+  WebRuntimeFeatures::EnablePictureInPictureAPI(false);
 #else  // defined(OS_ANDROID)
   WebRuntimeFeatures::EnableNavigatorContentUtils(true);
   // Tracking bug for the implementation: https://crbug.com/728609

third_party/WebKit/LayoutTests/virtual/stable/webexposed/element-instance-property-listing-expected.txt

@@ -1054,6 +1054,7 @@ html element video
     property currentTime
     property defaultMuted
     property defaultPlaybackRate
+    property disablePictureInPicture
     property disableRemotePlayback
     property duration
     property ended
@@ -1065,6 +1066,8 @@ html element video
     property muted
     property networkState
     property onencrypted
+    property onenterpictureinpicture
+    property onleavepictureinpicture
     property onwaitingforkey
     property pause
     property paused
@@ -1075,6 +1078,7 @@ html element video
     property preload
     property readyState
     property remote
+    property requestPictureInPicture
     property seekable
     property seeking
     property setMediaKeys

third_party/WebKit/LayoutTests/virtual/stable/webexposed/global-interface-listing-expected.txt

@@ -1279,6 +1279,8 @@ interface Document : Node
     getter onwebkitfullscreenerror
     getter onwheel
     getter origin
+    getter pictureInPictureElement
+    getter pictureInPictureEnabled
     getter plugins
     getter pointerLockElement
     getter readyState
@@ -1326,6 +1328,7 @@ interface Document : Node
     method elementsFromPoint
     method evaluate
     method execCommand
+    method exitPictureInPicture
     method exitPointerLock
     method getElementById
     method getElementsByClassName
@@ -3278,7 +3281,10 @@ interface HTMLUnknownElement : HTMLElement
     method constructor
 interface HTMLVideoElement : HTMLMediaElement
     attribute @@toStringTag
+    getter disablePictureInPicture
     getter height
+    getter onenterpictureinpicture
+    getter onleavepictureinpicture
     getter poster
     getter videoHeight
     getter videoWidth
@@ -3288,11 +3294,15 @@ interface HTMLVideoElement : HTMLMediaElement
     getter webkitSupportsFullscreen
     getter width
     method constructor
+    method requestPictureInPicture
     method webkitEnterFullScreen
     method webkitEnterFullscreen
     method webkitExitFullScreen
     method webkitExitFullscreen
+    setter disablePictureInPicture
     setter height
+    setter onenterpictureinpicture
+    setter onleavepictureinpicture
     setter poster
     setter width
 interface HashChangeEvent : Event
@@ -4457,6 +4467,13 @@ interface PhotoCapabilities
     getter imageWidth
     getter redEyeReduction
     method constructor
+interface PictureInPictureWindow : EventTarget
+    attribute @@toStringTag
+    getter height
+    getter onresize
+    getter width
+    method constructor
+    setter onresize
 interface Plugin
     attribute @@toStringTag
     getter description
@@ -6092,6 +6109,7 @@ interface ShadowRoot : DocumentFragment
     getter host
     getter innerHTML
     getter mode
+    getter pictureInPictureElement
     getter pointerLockElement
     getter styleSheets
     method constructor

third_party/blink/public/platform/web_runtime_features.h

@@ -123,6 +123,7 @@ class WebRuntimeFeatures {
   BLINK_PLATFORM_EXPORT static void EnablePaymentRequest(bool);
   BLINK_PLATFORM_EXPORT static void EnablePermissionsAPI(bool);
   BLINK_PLATFORM_EXPORT static void EnablePictureInPicture(bool);
+  BLINK_PLATFORM_EXPORT static void EnablePictureInPictureAPI(bool);
   BLINK_PLATFORM_EXPORT static void EnablePreciseMemoryInfo(bool);
   BLINK_PLATFORM_EXPORT static void EnablePreloadDefaultIsMetadata(bool);
   BLINK_PLATFORM_EXPORT static void EnablePreloadImageSrcSetEnabled(bool);

third_party/blink/renderer/platform/exported/web_runtime_features.cc

@@ -288,6 +288,10 @@ void WebRuntimeFeatures::EnablePictureInPicture(bool enable) {
   RuntimeEnabledFeatures::SetPictureInPictureEnabled(enable);
 }
 
+void WebRuntimeFeatures::EnablePictureInPictureAPI(bool enable) {
+  RuntimeEnabledFeatures::SetPictureInPictureAPIEnabled(enable);
+}
+
 void WebRuntimeFeatures::EnablePreloadDefaultIsMetadata(bool enable) {
   RuntimeEnabledFeatures::SetPreloadDefaultIsMetadataEnabled(enable);
 }

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -965,9 +965,10 @@
       name: "PictureInPicture",
       settable_from_internals: true,
     },
+    // Picture-in-Picture API is disabled by default on Android.
     {
       name: "PictureInPictureAPI",
-      status: "experimental",
+      status: "stable",
     },
     {
       name: "PreciseMemoryInfo",