Tiling priorities in Android Webview.

android_webview/browser/hardware_renderer.cc

Index: android_webview/browser/hardware_renderer.cc
diff --git a/android_webview/browser/hardware_renderer.cc b/android_webview/browser/hardware_renderer.cc
index 4ed2859b1399038a5dd060058b0bfcd450158404..12c474cb2c17d7afae9e30534b6a7a2be3d59865 100644
--- a/android_webview/browser/hardware_renderer.cc
+++ b/android_webview/browser/hardware_renderer.cc
@@ -188,10 +188,10 @@ void HardwareRenderer::DrawGL(bool stencil_enabled,
 
   viewport_.SetSize(draw_info->width, draw_info->height);
   layer_tree_host_->SetViewportSize(viewport_);
-  clip_.SetRect(draw_info->clip_left,
-                draw_info->clip_top,
-                draw_info->clip_right - draw_info->clip_left,
-                draw_info->clip_bottom - draw_info->clip_top);
+  gfx::Rect clip(draw_info->clip_left,
+                 draw_info->clip_top,
+                 draw_info->clip_right - draw_info->clip_left,
+                 draw_info->clip_bottom - draw_info->clip_top);
   stencil_enabled_ = stencil_enabled;
 
   gfx::Transform transform(gfx::Transform::kSkipInitialization);
@@ -203,10 +203,20 @@ void HardwareRenderer::DrawGL(bool stencil_enabled,
   {
     base::AutoReset<bool> frame_resetter(&viewport_clip_valid_for_dcheck_,
                                          true);
-    layer_tree_host_->SetNeedsRedrawRect(clip_);
+    layer_tree_host_->SetNeedsRedrawRect(clip);
     layer_tree_host_->Composite(gfx::FrameTime::Now());
   }
   gl_surface_->ResetBackingFrameBufferObject();
+
+  // Need to post the new transform matrix and clip back to child compositor
+  // because there is no onDraw during a Render Thread animation, and child
+  // compositor might not have the tiles rasterized as the animation goes on.
+  if (transform != transform_ || clip != clip_) {
+    transform_ = transform;
+    clip_ = clip;

[boliu, 2014/07/16 17:25:10]

child shouldn't need the clip, clip isn't suitable for tile management since it
can jump around wildly

[hush (inactive), 2014/07/16 20:45:32]

okay.
I also change the function name to PostExternalMatrixToChildCompositor.

On 2014/07/16 17:25:10, boliu wrote:

+    shared_renderer_state_->PostExternalDrawConstraintsToChildCompositor(
+        clip_, transform_);
+  }
 }
 
 scoped_ptr<cc::OutputSurface> HardwareRenderer::CreateOutputSurface(