GitLab

Modernize the interface for JavaRef and its subclasses - make better use
of C++11 features, and mark existing confusing/easily misused APIs as
deprecated. Also. fully reformat the file while it's being changed this
much.

Notable changes:
 - JavaRef can now be converted to bool in bool contexts, so "if (obj)"
   works and "!obj.is_null()" is no longer necessary.
 - ScopedJavaLocalRef<T>::Adopt() now exists to make it more explicit
   that the caller is adopting an existing reference, not creating a new
   one. This should only be used when dealing with return values from
   JNIEnv methods.
 - Conversion constructors/assignments now exist, allowing for example
   JavaRef<jstring> to be assigned to ScopedJavaLocalRef<jobject>.
 - Local references can be constructed or assigned from global
   references and vice versa without needing to use Reset().
 - Confusing forms of Reset() that take different parameters, or behave
   differently from, construction/assignment have been deprecated.

The new API is intended to be somewhat similar to scoped_refptr, which
is the closest native equivalent.

Bug: 519562
Test: base_unittests
Change-Id: I8a989dd04b357e83bc2a28a6ec9b7e14495ccbd2
Reviewed-on: https://chromium-review.googlesource.com/c/1262115
Commit-Queue: Richard Coles <torne@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#598800}