[Picture-in-Picture] Disable if no GPU compositing.

This is a temporary fix that sets document.pictureInPictureEnabled to
false in the case of disabling the GPU.

Bug: 806249, 807840
Change-Id: I84445a0231b46cfbd0bb2f25eaca53f96604ce55
Reviewed-on: https://chromium-review.googlesource.com/1042290
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556438}

content/renderer/render_view_impl.cc

@@ -966,7 +966,14 @@ void RenderView::ApplyWebPreferences(const WebPreferences& prefs,
       static_cast<blink::WebEffectiveConnectionType>(
           prefs.low_priority_iframes_threshold));
 
+  // TODO(crbug.com/806249): Remove this once Picture-in-Picture is compatible
+  // without GPU compositing.
+  RenderThreadImpl* render_thread = RenderThreadImpl::current();
+  if (render_thread && render_thread->IsGpuCompositingDisabled()) {
+    settings->SetPictureInPictureEnabled(false);
+  } else {
     settings->SetPictureInPictureEnabled(prefs.picture_in_picture_enabled);
+  }
 
 #if defined(OS_MACOSX)
   settings->SetDoubleTapToZoomEnabled(true);