Implement asynchronous operation for RWHVP::CopyFromCompositingSurface on Mac

content/browser/renderer_host/compositing_iosurface_mac.h

Index: content/browser/renderer_host/compositing_iosurface_mac.h
diff --git a/content/browser/renderer_host/compositing_iosurface_mac.h b/content/browser/renderer_host/compositing_iosurface_mac.h
index 7fa3ece56d9019857da09978ac759dd59068797c..d6b95041f509c9d690364605c4db38f8369178d3 100644
--- a/content/browser/renderer_host/compositing_iosurface_mac.h
+++ b/content/browser/renderer_host/compositing_iosurface_mac.h
@@ -9,12 +9,14 @@
 #import <QuartzCore/CVDisplayLink.h>
 #include <QuartzCore/QuartzCore.h>
 
+#include "base/callback.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/scoped_nsobject.h"
 #include "base/synchronization/lock.h"
 #include "base/time.h"
 #include "base/timer.h"
 #include "ui/gfx/native_widget_types.h"
+#include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 
 class IOSurfaceSupport;
@@ -49,9 +51,12 @@ class CompositingIOSurfaceMac {
   // |src_pixel_subrect| and |dst_pixel_size| are not in DIP but in pixel.
   // Caller must ensure that |out| is allocated with the size no less than
   // |4 * dst_pixel_size.width() * dst_pixel_size.height()| bytes.
-  bool CopyTo(const gfx::Rect& src_pixel_subrect,
+  // |callback| is invoked when the operation is completed or failed.
+  // Do no call this method again before |callback| is invoked.
+  void CopyTo(const gfx::Rect& src_pixel_subrect,
               const gfx::Size& dst_pixel_size,
-              void* out);
+              void* out,
+              const base::Callback<void(bool)>& callback);
 
   // Unref the IOSurface and delete the associated GL texture. If the GPU
   // process is no longer referencing it, this will delete the IOSurface.
@@ -143,6 +148,36 @@ class CompositingIOSurfaceMac {
     SurfaceVertex verts_[4];
   };
 
+  // Keeps track of states and buffers for asynchronous readback of IOSurface.
+  struct CopyContext {
+    CopyContext();
+    ~CopyContext();
+
+    void Reset() {
+      started = false;
+      cycles_elapsed = 0;
+      frame_buffer = 0;
+      frame_buffer_texture = 0;
+      pixel_buffer = 0;
+      use_fence = false;
+      fence = 0;
+      out_buf = NULL;
+      callback.Reset();
+    }
+
+    bool started;
+    int cycles_elapsed;
+    GLuint frame_buffer;
+    GLuint frame_buffer_texture;
+    GLuint pixel_buffer;
+    bool use_fence;
+    GLuint fence;
+    gfx::Rect src_rect;
+    gfx::Size dest_size;
+    void* out_buf;
+    base::Callback<void(bool)> callback;
+  };
+
   CompositingIOSurfaceMac(IOSurfaceSupport* io_surface_support,
                           NSOpenGLContext* glContext,
                           CGLContextObj cglContext,
@@ -172,6 +207,9 @@ class CompositingIOSurfaceMac {
   void StartOrContinueDisplayLink();
   void StopDisplayLink();
 
+  void FinishCopy();
+  void CleanupResourcesForCopy();
+
   // Cached pointer to IOSurfaceSupport Singleton.
   IOSurfaceSupport* io_surface_support_;
 
@@ -194,6 +232,11 @@ class CompositingIOSurfaceMac {
   // with it.
   GLuint texture_;
 
+  CopyContext copy_context_;
+
+  // Timer for finishing a copy operation.
+  base::RepeatingTimer<CompositingIOSurfaceMac> copy_timer_;
+
   // Shader parameters.
   GLuint shader_program_blit_rgb_;
   GLint blit_rgb_sampler_location_;