This is initial API support required for enabling SurfaceTexture backed zero-copy for Android

ui/gl/android/surface_texture.h

Index: ui/gl/android/surface_texture.h
diff --git a/ui/gl/android/surface_texture.h b/ui/gl/android/surface_texture.h
index 62e375f796f45959e1ca0de2e37b7144c5e66ba3..0540a948974c5746fffc655209971bd005039b19 100644
--- a/ui/gl/android/surface_texture.h
+++ b/ui/gl/android/surface_texture.h
@@ -21,7 +21,9 @@ namespace gfx {
 class GL_EXPORT SurfaceTexture
     : public base::RefCountedThreadSafe<SurfaceTexture>{
  public:
-  explicit SurfaceTexture(int texture_id);
+  static scoped_refptr<SurfaceTexture> Create(int texture_id);
+
+  static scoped_refptr<SurfaceTexture> CreateSingleBuffered(int texture_id);
 
   // Set the listener callback, which will be invoked on the same thread that
   // is being called from here for registration.
@@ -33,6 +35,11 @@ class GL_EXPORT SurfaceTexture
   // Update the texture image to the most recent frame from the image stream.
   void UpdateTexImage();
 
+  // Release the texture content. This is needed, and supported only in single
+  // buffered mode to allow the image content producer to take ownership
+  // of the image buffer.

[bulach, 2014/03/11 16:13:17]

nit: I'd be even more explicit:
this is *only* supported on SurfaceTexture instantiated via
|CreateSingleBuffered(...)|.

+  void ReleaseTexImage();
+
   // Retrieve the 4x4 texture coordinate transform matrix associated with the
   // texture image set by the most recent call to updateTexImage.
   void GetTransformMatrix(float mtx[16]);
@@ -57,8 +64,14 @@ class GL_EXPORT SurfaceTexture
     return j_surface_texture_;
   }
 
+  static bool IsSingleBufferModeSupported();

[bulach, 2014/03/11 16:13:17]

nit: hmm... do we need a non-static method too?

I'm thinking about the following pattern:
scoped_refptr<SurfaceTexture> s = SurfaceTexture::Create(0);
if (SurfaceTexture::IsSingleBufferModeSupported()) {
  s->ReleaseTexImage();
}


should we document that this should only be used to guard the
CreateSingleBuffered() call?

+
   static bool RegisterSurfaceTexture(JNIEnv* env);
 
+ protected:
+  explicit SurfaceTexture(
+      const base::android::ScopedJavaLocalRef<jobject>& j_surface_texture);
+
  private:
   friend class base::RefCountedThreadSafe<SurfaceTexture>;
   ~SurfaceTexture();