Telemtry: hooks "chrome.gpuBenchmarking.smoothScrollBy" with java on android.

content/browser/renderer_host/smooth_scroll_gesture_android.cc

+// Copyright (c) 2012 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 "content/browser/renderer_host/smooth_scroll_gesture_android.h"
+
+#include "base/debug/trace_event.h"
+#include "content/browser/renderer_host/render_widget_host_impl.h"
+#include "jni/SmoothScroller_jni.h"
+
+namespace {
+bool g_jni_initialized = false;
+
+void RegisterNativesIfNeeded(JNIEnv* env) {
+  if (!g_jni_initialized) {
+    content::RegisterNativesImpl(env);
+    g_jni_initialized = true;
+  }
+}
+}  // namespace
+
+namespace content {
+
+SmoothScrollGestureAndroid::SmoothScrollGestureAndroid(
+    int pixels_to_scroll,
+    RenderWidgetHost* rwh,
+    base::android::ScopedJavaLocalRef<jobject> java_scroller)
+    : pixels_scrolled_(0),
+      has_started_(false),
+      pixels_to_scroll_(pixels_to_scroll),
+      rwh_(rwh),
+      java_scroller_(java_scroller) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  RegisterNativesIfNeeded(env);
+}
+
+SmoothScrollGestureAndroid::~SmoothScrollGestureAndroid() {
+}
+
+bool SmoothScrollGestureAndroid::ForwardInputEvents(
+    base::TimeTicks now, RenderWidgetHost* host) {
+  if (!has_started_) {
+    has_started_ = true;
+    JNIEnv* env = base::android::AttachCurrentThread();
+    Java_SmoothScroller_start(
+        env, java_scroller_.obj(), reinterpret_cast<int>(this));
+  }
+
+  TRACE_COUNTER_ID1(
+      "gpu", "smooth_scroll_by_pixels_scrolled", this, pixels_scrolled_);
+
+  return pixels_scrolled_ < pixels_to_scroll_;
+}
+
+double SmoothScrollGestureAndroid::Tick(JNIEnv* env, jobject obj) {
+  double delta = SmoothScrollGesture::Tick(
+      base::TimeTicks::HighResNow(),
+      RenderWidgetHostImpl::From(rwh_)->SyntheticScrollMessageInterval());
+  pixels_scrolled_ += delta;
+  return delta;
+}
+
+bool SmoothScrollGestureAndroid::HasFinished(JNIEnv* env, jobject obj) {
+  return pixels_scrolled_ >= pixels_to_scroll_;
+}
+
+}  // namespace content
+