Adding UMA on page load size for pages with Media

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
index a3a195c2fcc3b2a7ca372c8415f8bea99985f949..7acb0d5b19c72ff20aeaada1d1a9d85ac1a98562 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -26,6 +26,7 @@
 
 #include "core/html/HTMLMediaElement.h"
 
+#include <limits>
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/Microtask.h"
 #include "bindings/core/v8/ScriptController.h"
@@ -68,6 +69,7 @@
 #include "core/layout/LayoutMedia.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
+#include "core/loader/DocumentLoader.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
 #include "core/page/ChromeClient.h"
@@ -87,6 +89,7 @@
 #include "public/platform/WebAudioSourceProvider.h"
 #include "public/platform/WebContentDecryptionModule.h"
 #include "public/platform/WebInbandTextTrack.h"
+#include "public/platform/WebLoadingBehaviorFlag.h"
 #include "public/platform/WebMediaPlayerSource.h"
 #include "public/platform/WebMediaStream.h"
 #include "public/platform/modules/remoteplayback/WebRemotePlaybackAvailability.h"
@@ -97,7 +100,6 @@
 #include "wtf/MathExtras.h"
 #include "wtf/PtrUtil.h"
 #include "wtf/text/CString.h"
-#include <limits>
 
 #ifndef BLINK_MEDIA_LOG
 #define BLINK_MEDIA_LOG DVLOG(3)
@@ -2317,6 +2319,9 @@ void HTMLMediaElement::playInternal() {
     scheduleResolvePlayPromises();
   }
 
+  document().loader()->didObserveLoadingBehavior(

[Bryan McQuade, 2017/03/08 18:03:22]

one thing to note - this may prevent you from discovering loading behaviors in
child iframes (e.g. youtube iframe embeds). you may want to report the loading
behavior on the top-level document if you want to know about media loads in
child frames (and update the comment in the enum to note that this is reported
for media played in child frames)

[Bryan McQuade, 2017/03/08 18:10:11]

charles and i just chatted - due to OOPIF, we think the best way forward here is
to send IPCs for child frames, and then join things up browser-side. turns out
this bug affects my subresource filter page load metrics as well (i want to
track cases where subresources are filtered in child frames) so i'll take a look
at fixing this now.

[RyanSturm, 2017/03/08 18:17:11]

Agreed. I made the bad assumption that this was already happening due to the
other places that use this. Keep more on board with the solution that you are
considering for tracking child frames in the browser MetricsWCO.

[mlamouri (slow - plz ping), 2017/03/13 18:38:27]

Instead of adding more plumbing, why not re-using
WebContentsObserver::MediaStartedPlaying? It should be fairly similar to what
you are doing except that you know the media actually loaded (ie. a 404 media
would likely hit your new plumbing).

[RyanSturm, 2017/03/13 23:38:24]

Thanks for the pointer. That looks like a better approach.

+      WebLoadingBehaviorFlag::WebLoadingBehaviorMediaPlayed);
+
   m_canAutoplay = false;
 
   setIgnorePreloadNone();