Make virtual method pure virtual

android_webview/browser/compositor_frame_consumer.h

Index: android_webview/browser/compositor_frame_consumer.h
diff --git a/android_webview/browser/compositor_frame_consumer.h b/android_webview/browser/compositor_frame_consumer.h
index 0d5af1d9a268daa0f0e6199a524807b549c676a8..cf7d1d6b06c693a072af5e1138ee0ec85fd47d98 100644
--- a/android_webview/browser/compositor_frame_consumer.h
+++ b/android_webview/browser/compositor_frame_consumer.h
@@ -43,7 +43,7 @@ class CompositorFrameConsumer {
   virtual void SetScrollOffsetOnUI(gfx::Vector2d scroll_offset) = 0;
   // Returns uncommitted frame to be returned, if any.
   virtual std::unique_ptr<ChildFrame> SetFrameOnUI(
-      std::unique_ptr<ChildFrame> frame);
+      std::unique_ptr<ChildFrame> frame) = 0;
   virtual void InitializeHardwareDrawIfNeededOnUI() = 0;
   virtual ParentCompositorDrawConstraints GetParentDrawConstraintsOnUI()
       const = 0;