[Android WebView] Migrate the rendering code to a separate set of classes.

android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java

+// Copyright (c) 2013 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 android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Picture;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+
+/**
+ * Provides auxiliary methods related to Picture objects and native SkPictures.
+ */
+@JNINamespace("android_webview")
+public class JavaBrowserViewRendererHelper {
+
+    /**
+     * Provides a Bitmap object with a given width and height used for auxiliary rasterization.
+     */
+    @CalledByNative
+    private static Bitmap createBitmap(int width, int height) {
+        return Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+    }
+
+    /**
+     * Draws a provided bitmap into a canvas.
+     * Used for convenience from the native side and other static helper methods.
+     */
+    @CalledByNative
+    private static void drawBitmapIntoCanvas(Bitmap bitmap, Canvas canvas) {
+        canvas.drawBitmap(bitmap, 0, 0, null);
+    }
+
+    /**
+     * Creates a new Picture that records drawing a provided bitmap.
+     * Will return an empty Picture if the Bitmap is null.
+     */
+    @CalledByNative
+    private static Picture recordBitmapIntoPicture(Bitmap bitmap) {
+        Picture picture = new Picture();
+        if (bitmap != null) {
+            Canvas recordingCanvas = picture.beginRecording(bitmap.getWidth(), bitmap.getHeight());
+            drawBitmapIntoCanvas(bitmap, recordingCanvas);
+            picture.endRecording();
+        }
+        return picture;
+    }
+
+    // Should never be instantiated.
+    private JavaBrowserViewRendererHelper() {
+    }
+}