customtabs: Send time to first contentful paint to the caller.

chrome/browser/page_load_metrics/observers/android_page_load_metrics_observer.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/page_load_metrics/observers/android_page_load_metrics_observer.h"
+
+#include <string>
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "base/android/scoped_java_ref.h"
+#include "components/page_load_metrics/browser/page_load_metrics_util.h"

[Bryan McQuade, 2016/07/26 23:44:27]

same - need to update include path

[Benoit L, 2016/07/27 16:23:45]

Done.

+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/web_contents.h"
+#include "jni/PageLoadMetrics_jni.h"
+#include "url/gurl.h"
+
+AndroidPageLoadMetricsObserver::AndroidPageLoadMetricsObserver(
+    content::WebContents* web_contents)
+    : web_contents_(web_contents) {}
+
+void AndroidPageLoadMetricsObserver::OnFirstContentfulPaint(
+    const page_load_metrics::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

[Bryan McQuade, 2016/07/26 14:29:33]

if we want to cases where a page is backgrounded before FCP, you can add:

  if (!WasStartedInForegroundOptionalEventInForeground(
          timing.first_contentful_paint, info)) {
      return;
  }

(see earlier comment for more reason as to why we might want to do this)

[Benoit L, 2016/07/27 16:23:45]

I guess there are two ways to look at how to proceed here:
(a) Only pass the "raw" events to Java, and let the Java side handle the
filtering
(b) Provide an already filtered metric to the Java side.

I erred on the side of option (a) since it's more flexible, but I'm not firmly
convinced it's the best approach.

What do you think?

+  int64_t first_contentful_paint_ms =
+      timing.first_contentful_paint->InMilliseconds();
+  base::android::ScopedJavaLocalRef<jobject> java_web_contents =
+      web_contents_->GetJavaWebContents();
+  JNIEnv* env = base::android::AttachCurrentThread();
+  Java_PageLoadMetrics_onFirstContentfulPaint(
+      env, java_web_contents.obj(),
+      static_cast<jlong>(first_contentful_paint_ms));
+}
+
+bool RegisterPageLoadMetricsBindings(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}