Implement transform/clip support for Android WebView.

cc/output/direct_renderer.cc

Index: cc/output/direct_renderer.cc
diff --git a/cc/output/direct_renderer.cc b/cc/output/direct_renderer.cc
index 429ac22bc5de82624461d1bdff5fc5e7949a4369..d87ba289b6aa02789543483bd23ecc18aee1e348 100644
--- a/cc/output/direct_renderer.cc
+++ b/cc/output/direct_renderer.cc
@@ -80,6 +80,7 @@ void DirectRenderer::QuadRectTransform(gfx::Transform* quad_rect_transform,
 
 // static
 void DirectRenderer::InitializeMatrices(DrawingFrame* frame,
+                                        gfx::Vector2d offset,
                                         gfx::Rect draw_rect,
                                         bool flip_y) {
   if (flip_y) {
@@ -93,12 +94,12 @@ void DirectRenderer::InitializeMatrices(DrawingFrame* frame,
                                                      draw_rect.y(),
                                                      draw_rect.bottom());
   }
-  frame->window_matrix =
-      window_matrix(0, 0, draw_rect.width(), draw_rect.height());
+
+  frame->window_matrix = window_matrix(
+      offset.x(), offset.y(), draw_rect.width(), draw_rect.height());
   frame->flipped_y = flip_y;
 }
 
-// static
 gfx::Rect DirectRenderer::MoveScissorToWindowSpace(
     const DrawingFrame* frame, const gfx::RectF& scissor_rect) {
   gfx::Rect scissor_rect_in_canvas_space = gfx::ToEnclosingRect(scissor_rect);
@@ -116,6 +117,8 @@ gfx::Rect DirectRenderer::MoveScissorToWindowSpace(
     scissor_rect_in_canvas_space.set_y(
         scissor_rect_in_canvas_space.y() - framebuffer_output_rect.y());
   }
+  if (!frame->current_texture)
+    scissor_rect_in_canvas_space.Offset(client_->DeviceViewportOffset());
   return scissor_rect_in_canvas_space;
 }
 
@@ -323,8 +326,13 @@ bool DirectRenderer::UseRenderPass(DrawingFrame* frame,
 
   if (render_pass == frame->root_render_pass) {
     BindFramebufferToOutputSurface(frame);
-    InitializeMatrices(frame, render_pass->output_rect, FlippedFramebuffer());
-    SetDrawViewportSize(render_pass->output_rect.size());
+    InitializeMatrices(frame,
+                       client_->DeviceViewportOffset(),
+                       render_pass->output_rect,
+                       FlippedFramebuffer());
+    SetDrawViewport(
+        gfx::Rect(gfx::PointAtOffsetFromOrigin(client_->DeviceViewportOffset()),
+                  render_pass->output_rect.size()));
     return true;
   }