aw: Fix backdrop filter

Properly set the GLSurface size.

Bug: 990535
Change-Id: If5d5cc513693463d994d07f5361996db795f4a8d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1742208Reviewed-by: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685210}

android_webview/browser/gfx/aw_gl_surface.cc

@@ -55,6 +55,10 @@ bool AwGLSurface::Resize(const gfx::Size& size,
   return true;
 }
 
+void AwGLSurface::SetSize(const gfx::Size& size) {
+  size_ = size;
+}
+
 void AwGLSurface::MaybeDidPresent(gfx::PresentationFeedback feedback) {
   if (pending_presentation_callback_.is_null())
     return;

android_webview/browser/gfx/aw_gl_surface.h

@@ -31,6 +31,7 @@ class AwGLSurface : public gl::GLSurface {
               ColorSpace color_space,
               bool has_alpha) override;
 
+  void SetSize(const gfx::Size& size);
   void MaybeDidPresent(gfx::PresentationFeedback feedback);
 
  protected:

android_webview/browser/gfx/surfaces_instance.cc

@@ -241,6 +241,7 @@ void SurfacesInstance::DrawAndSwap(const gfx::Size& viewport,
     // GL state could be changed across frames, so we need reset GrContext.
     shared_context_state_->PessimisticallyResetGrContext();
   }
+  gl_surface_->SetSize(viewport);
   display_->Resize(viewport);
   display_->DrawAndSwap();
   // SkiaRenderer generates DidReceiveSwapBuffersAck calls.