Cache auxiliary bitmap across draw frames

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

Index: android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java
diff --git a/android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java b/android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java
index d4e79c82254e6fd7d9471c49156913afbf9f2f78..7abf59c380b0107e5693bbb41422f3d413b2d570 100644
--- a/android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java
+++ b/android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java
@@ -11,6 +11,9 @@ import android.graphics.Picture;
 
 import org.chromium.base.CalledByNative;
 import org.chromium.base.JNINamespace;
+import org.chromium.content.common.TraceEvent;
+
+import java.lang.ref.SoftReference;
 
 /**
  * Provides auxiliary methods related to Picture objects and native SkPictures.
@@ -18,12 +21,29 @@ import org.chromium.base.JNINamespace;
 @JNINamespace("android_webview")
 public class JavaBrowserViewRendererHelper {
 
+    private static SoftReference<Bitmap> sCachedBitmap;
+
     /**
      * 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);
+    private static Bitmap createBitmap(int width, int height, boolean cacheResult) {
+        if (cacheResult && sCachedBitmap != null) {
+            Bitmap result = sCachedBitmap.get();
+            if (result != null) {
+                if (result.getWidth() == width && result.getHeight() == height) {
+                    TraceEvent.instant("Reused cached bitmap");
+                    return result;
+                }
+                result.recycle();
+            }
+            sCachedBitmap = null;
+        }
+        Bitmap result = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+        if (cacheResult) {
+            sCachedBitmap = new SoftReference<Bitmap>(result);
+        }
+        return result;
     }
 
     /**