ui: Use single buffer SurfaceTexture mode for native GpuMemoryBuffers on Android.

ui/gl/android/surface_texture.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GL_ANDROID_SURFACE_TEXTURE_H_
 #define UI_GL_ANDROID_SURFACE_TEXTURE_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "ui/gl/gl_export.h"
 
 struct ANativeWindow;
 
 namespace gfx {
 
 // This class serves as a bridge for native code to call java functions inside
 // android SurfaceTexture class.
 class GL_EXPORT SurfaceTexture
     : public base::RefCountedThreadSafe<SurfaceTexture>{
  public:
   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.
   // Note: Since callbacks come in from Java objects that might outlive objects
   // being referenced from the callback, the only robust way here is to create
   // the callback from a weak pointer to your object.
   void SetFrameAvailableCallback(const base::Closure& callback);
 
   // Update the texture image to the most recent frame from the image stream.
   void UpdateTexImage();
 
+  // Release the texture content. This is needed only in single buffered mode
+  // to allow the image content producer to take ownership
+  // of the image buffer.
+  // 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]);
 
   // Attach the SurfaceTexture to the texture currently bound to
   // GL_TEXTURE_EXTERNAL_OES.
   void AttachToGLContext();
 
   // Detaches the SurfaceTexture from the context that owns its current GL
   // texture. Must be called with that context current on the calling thread.
   void DetachFromGLContext();
 
   // Creates a native render surface for this surface texture.
   // The caller must release the underlying reference when done with the handle
   // by calling ANativeWindow_release().
   ANativeWindow* CreateSurface();
 
   const base::android::JavaRef<jobject>& j_surface_texture() const {
     return j_surface_texture_;
   }
 
+  // This should only be used to guard the SurfaceTexture instantiated via
+  // |CreateSingleBuffered(...)|
+  static bool IsSingleBufferModeSupported();
+
   static bool RegisterSurfaceTexture(JNIEnv* env);
 
  protected:
   explicit SurfaceTexture(
       const base::android::ScopedJavaLocalRef<jobject>& j_surface_texture);
 
  private:
   friend class base::RefCountedThreadSafe<SurfaceTexture>;
   ~SurfaceTexture();
 
   // Java SurfaceTexture instance.
   base::android::ScopedJavaGlobalRef<jobject> j_surface_texture_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceTexture);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_ANDROID_SURFACE_TEXTURE_H_