Partial swaps on OSX

content/browser/renderer_host/accelerated_surface_container_mac.cc

Index: content/browser/renderer_host/accelerated_surface_container_mac.cc
diff --git a/content/browser/renderer_host/accelerated_surface_container_mac.cc b/content/browser/renderer_host/accelerated_surface_container_mac.cc
index e76103ce5711492fadee3e1187da071ad1b23139..86875f3c09f36179fd3cd92db4ac6f37dc49a0fa 100644
--- a/content/browser/renderer_host/accelerated_surface_container_mac.cc
+++ b/content/browser/renderer_host/accelerated_surface_container_mac.cc
@@ -118,21 +118,38 @@ void AcceleratedSurfaceContainerMac::Draw(CGLContextObj context) {
   }
   // If using TransportDIBs, the texture needs to be uploaded every frame.
   if (transport_dib_.get() != NULL) {
-    void* pixel_memory = transport_dib_->memory();
+    unsigned char* pixel_memory =
+        static_cast<unsigned char*>(transport_dib_->memory());
     if (pixel_memory) {
       glBindTexture(target, texture_);
       glPixelStorei(GL_UNPACK_ALIGNMENT, 1);  // Needed for NPOT textures.
-      glTexSubImage2D(target,
-                      0,  // mipmap level 0
-                      0,  // x-offset
-                      0,  // y-offset
-                      width_,
-                      height_,
-                      GL_BGRA,  // The GPU plugin gave us BGRA pixels
-                      GL_UNSIGNED_INT_8_8_8_8_REV,
-                      pixel_memory);
+      if (update_rect_.IsEmpty()) {
+        glTexSubImage2D(target,
+                        0,  // mipmap level 0
+                        0,  // x-offset
+                        0,  // y-offset
+                        width_,
+                        height_,
+                        GL_BGRA,  // The GPU plugin gave us BGRA pixels
+                        GL_UNSIGNED_INT_8_8_8_8_REV,
+                        pixel_memory);
+      } else {
+        glPixelStorei(GL_UNPACK_ROW_LENGTH, width_);
+        glTexSubImage2D(target,
+                        0,  // mipmap level 0
+                        update_rect_.x(),  // x-offset
+                        update_rect_.y(),  // y-offset
+                        update_rect_.width(),
+                        update_rect_.height(),
+                        GL_BGRA,  // The GPU plugin gave us BGRA pixels
+                        GL_UNSIGNED_INT_8_8_8_8_REV,
+                        &pixel_memory[(update_rect_.x() +
+                                       update_rect_.y() * width_) * 4]);
+        glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
+      }
     }
   }
+  update_rect_ = gfx::Rect();
 
   if (texture_) {
     int texture_width = io_surface_support ? surface_width_ : width_;
@@ -203,6 +220,27 @@ bool AcceleratedSurfaceContainerMac::ShouldBeVisible() const {
 }
 
 void AcceleratedSurfaceContainerMac::set_was_painted_to(uint64 surface_id) {
+  set_was_painted_to_common(surface_id);
+  update_rect_ = gfx::Rect();
+}
+
+void AcceleratedSurfaceContainerMac::set_was_painted_to(
+   uint64 surface_id,
+   const gfx::Rect& update_rect) {
+  set_was_painted_to_common(surface_id);
+  update_rect_ = update_rect_.Union(update_rect);
+}
+
+void AcceleratedSurfaceContainerMac::EnqueueTextureForDeletion() {
+  if (texture_) {
+    DCHECK(texture_pending_deletion_ == 0);
+    texture_pending_deletion_ = texture_;
+    texture_ = 0;
+  }
+}
+
+void AcceleratedSurfaceContainerMac::set_was_painted_to_common(
+    uint64 surface_id) {
   if (surface_id && (!surface_ || surface_id != surface_id_)) {
     // Keep the surface that was most recently painted to around.
     if (IOSurfaceSupport* io_surface_support = IOSurfaceSupport::Initialize()) {
@@ -222,12 +260,3 @@ void AcceleratedSurfaceContainerMac::set_was_painted_to(uint64 surface_id) {
   }
   was_painted_to_ = true;
 }
-
-void AcceleratedSurfaceContainerMac::EnqueueTextureForDeletion() {
-  if (texture_) {
-    DCHECK(texture_pending_deletion_ == 0);
-    texture_pending_deletion_ = texture_;
-    texture_ = 0;
-  }
-}
-