base: Add ScopedJavaLocalFrame class.

This class can be used to create a local reference frame. A local
reference frame ensures that some amount of local references can
be created and forces all references created in the frame to be
releases when exiting the frame.

BUG=360069
TBR=darin

Review URL: https://codereview.chromium.org/225283008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@262273 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 18 insertions, 0 deletions

diff --git a/base/android/scoped_java_ref.cc b/base/android/scoped_java_ref.cc
index 21b466e..bb6f503 100644
--- a/base/android/scoped_java_ref.cc
+++ b/base/android/scoped_java_ref.cc
@@ -9,6 +9,24 @@
 
 namespace base {
 namespace android {
+namespace {
+
+const int kDefaultLocalFrameCapacity = 16;
+
+}  // namespace
+
+ScopedJavaLocalFrame::ScopedJavaLocalFrame(JNIEnv* env) : env_(env) {
+  int failed = env_->PushLocalFrame(kDefaultLocalFrameCapacity);
+  DCHECK(!failed);
+}
+
+ScopedJavaLocalFrame::ScopedJavaLocalFrame(JNIEnv* env, int capacity)
+    : env_(env) {
+  int failed = env_->PushLocalFrame(capacity);
+  DCHECK(!failed);
+}
+
+ScopedJavaLocalFrame::~ScopedJavaLocalFrame() { env_->PopLocalFrame(NULL); }
 
 JavaRef<jobject>::JavaRef() : obj_(NULL) {}