Implement renderer importance API for WebView

android_webview/java/src/org/chromium/android_webview/AwRendererPriorityManager.java

+// Copyright 2017 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.
+
+package org.chromium.android_webview;
+
+import org.chromium.android_webview.renderer_priority.RendererPriority;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.content.browser.ChildProcessLauncher;
+
+/**
+ * Exposes an interface via which native code can manage the priority
+ * of a renderer process.
+ */
+@JNINamespace("android_webview")
+public class AwRendererPriorityManager {
+    @CalledByNative
+    private static void setRendererPriority(
+            int pid, @RendererPriority.RendererPriorityEnum int rendererPriority) {
+        // TODO(tobiasjs): handle RendererPriority.LOW separately from WAIVED.
+        ChildProcessLauncher.setInForeground(pid, rendererPriority == RendererPriority.HIGH);
+    }
+}