[android_webview] Use a fraction to calculate scroll offset.

content/browser/android/in_process/synchronous_compositor_impl.cc

Index: content/browser/android/in_process/synchronous_compositor_impl.cc
diff --git a/content/browser/android/in_process/synchronous_compositor_impl.cc b/content/browser/android/in_process/synchronous_compositor_impl.cc
index b04e85456f1d7f0095f97c66bc9f821f3f035731..e9092f8c918a78e6f5969e5e2b85ce7b418baf1e 100644
--- a/content/browser/android/in_process/synchronous_compositor_impl.cc
+++ b/content/browser/android/in_process/synchronous_compositor_impl.cc
@@ -415,6 +415,13 @@ void SynchronousCompositorImpl::DidActivatePendingTree() {
     compositor_client_->DidUpdateContent();
 }
 
+void SynchronousCompositorImpl::SetMaxScrollOffset(
+    gfx::Vector2dF max_scroll_offset) {
+  DCHECK(CalledOnValidThread());
+  if (compositor_client_)
+    compositor_client_->SetMaxRootLayerScrollOffset(max_scroll_offset);
+}
+
 void SynchronousCompositorImpl::SetTotalScrollOffset(gfx::Vector2dF new_value) {
   DCHECK(CalledOnValidThread());
   if (compositor_client_)
@@ -428,6 +435,18 @@ gfx::Vector2dF SynchronousCompositorImpl::GetTotalScrollOffset() {
   return gfx::Vector2dF();
 }
 
+void SynchronousCompositorImpl::SetPageScaleFactor(float page_scale_factor) {
+  DCHECK(CalledOnValidThread());
+  if (compositor_client_)
+    compositor_client_->SetRootLayerPageScaleFactor(page_scale_factor);
+}
+
+void SynchronousCompositorImpl::SetScrollableSize(gfx::SizeF scrollable_size) {
+  DCHECK(CalledOnValidThread());
+  if (compositor_client_)
+    compositor_client_->SetRootLayerScrollableSize(scrollable_size);
+}
+
 // Not using base::NonThreadSafe as we want to enforce a more exacting threading
 // requirement: SynchronousCompositorImpl() must only be used on the UI thread.
 bool SynchronousCompositorImpl::CalledOnValidThread() const {