Clear bitmap from canvas after done drawing to it.

Change-Id: I0ebc8510021a2dd0b147ced7890d939ec47809f6
diff --git a/src/com/android/browser/BookmarkUtils.java b/src/com/android/browser/BookmarkUtils.java
index 2e96613..ca0cfbc 100644
--- a/src/com/android/browser/BookmarkUtils.java
+++ b/src/com/android/browser/BookmarkUtils.java
@@ -104,6 +104,7 @@
                 drawFaviconToCanvas(context, favicon, canvas, iconBounds, type);
             }
         }
+        canvas.setBitmap(null);
         return bm;
     }
 
diff --git a/src/com/android/browser/Controller.java b/src/com/android/browser/Controller.java
index 0d22af0..142375d 100644
--- a/src/com/android/browser/Controller.java
+++ b/src/com/android/browser/Controller.java
@@ -1967,6 +1967,7 @@
         thumbnail.draw(canvas);
         Bitmap ret = Bitmap.createScaledBitmap(bm, width / filter_scale,
                 height / filter_scale, true);
+        canvas.setBitmap(null);
         bm.recycle();
         return ret;
     }
diff --git a/src/com/android/browser/Tab.java b/src/com/android/browser/Tab.java
index cd209ed..6aa8683 100644
--- a/src/com/android/browser/Tab.java
+++ b/src/com/android/browser/Tab.java
@@ -1993,6 +1993,7 @@
         float scale = mCaptureWidth / (float) mMainView.getWidth();
         c.scale(scale, scale, left, top);
         mMainView.draw(c);
+        c.setBitmap(null);
         persistThumbnail();
     }
 
diff --git a/src/com/android/browser/TabBar.java b/src/com/android/browser/TabBar.java
index 2b4dd63..d1652dd 100644
--- a/src/com/android/browser/TabBar.java
+++ b/src/com/android/browser/TabBar.java
@@ -243,6 +243,7 @@
         Canvas c = new Canvas(b);
         drawable.setBounds(0, 0, width, height);
         drawable.draw(c);
+        c.setBitmap(null);
         return b;
     }
 
diff --git a/src/com/android/browser/WallpaperHandler.java b/src/com/android/browser/WallpaperHandler.java
index cd896da..6437b1a 100644
--- a/src/com/android/browser/WallpaperHandler.java
+++ b/src/com/android/browser/WallpaperHandler.java
@@ -162,6 +162,7 @@
             Canvas canvas = new Canvas(bm);
             oldWallpaper.setBounds(0, 0, width, height);
             oldWallpaper.draw(canvas);
+            canvas.setBitmap(null);
             try {
                 wm.setBitmap(bm);
             } catch (IOException e) {