Enable use of video capture API for DevTools screencasting by default

Currently we only use video capture API for screencasting when
VizDisplayCompositor is enabled. Also use video capture API when
UseVideoCaptureApiForDevToolsSnapshots is enabled.

Bug: 813929
Change-Id: Ia3018eed1eda785a260227f89024d20b13da1a97
Reviewed-on: https://chromium-review.googlesource.com/1035616Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Saman Sami <samans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555439}

content/browser/devtools/protocol/page_handler.cc

@@ -47,6 +47,7 @@
 #include "content/public/browser/storage_partition.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "content/public/common/browser_side_navigation_policy.h"
+#include "content/public/common/content_features.h"
 #include "content/public/common/referrer.h"
 #include "content/public/common/result_codes.h"
 #include "content/public/common/use_zoom_for_dsf_policy.h"
@@ -199,7 +200,9 @@ PageHandler::PageHandler(EmulationHandler* emulation_handler)
       observer_(this),
       weak_factory_(this) {
 #if !defined(OS_ANDROID)
-  if (base::FeatureList::IsEnabled(features::kVizDisplayCompositor)) {
+  if (base::FeatureList::IsEnabled(features::kVizDisplayCompositor) ||
+      base::FeatureList::IsEnabled(
+          features::kUseVideoCaptureApiForDevToolsSnapshots)) {
     video_consumer_ = std::make_unique<DevToolsVideoConsumer>(
         base::BindRepeating(&PageHandler::OnFrameFromVideoConsumer,
                             weak_factory_.GetWeakPtr()));