Move scaling of ui resources for scrollbars to the time of upload

cc/resources/ui_resource_client.h

Index: cc/resources/ui_resource_client.h
diff --git a/cc/resources/ui_resource_client.h b/cc/resources/ui_resource_client.h
index 07d5fd8997f0b6bfabcf20cf9f817148285cd1f0..8bdca9c13b6177f311166f68ed73f57c9cd32bad 100644
--- a/cc/resources/ui_resource_client.h
+++ b/cc/resources/ui_resource_client.h
@@ -23,6 +23,10 @@ class CC_EXPORT UIResourceClient {
   // delete a UIResourceClient object after DeleteUIResource has been called for
   // all IDs associated with it.  A valid bitmap always must be returned but it
   // doesn't need to be the same size or format as the original.
+  // The bitmap's dimensions must *not* exceed the maximum texture size
+  // supported by the GPU. For resources that are o bigger than the viewport

[enne (OOO), 2016/08/24 20:51:09]

:o

+  // this should not be a problem, but for much larger resources, the caller is
+  // responsible for ensuring this.
   virtual UIResourceBitmap GetBitmap(UIResourceId uid,
                                      bool resource_lost) = 0;
   virtual ~UIResourceClient() {}