Rewire Android WebView's compositor changed signal.

android_webview/browser/compositor_id.h

Index: android_webview/browser/compositor_id.h
diff --git a/android_webview/browser/compositor_id.h b/android_webview/browser/compositor_id.h
new file mode 100644
index 0000000000000000000000000000000000000000..f644460a72ee372b426b67302ff0491a16f226cc
--- /dev/null
+++ b/android_webview/browser/compositor_id.h
@@ -0,0 +1,26 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ANDROID_WEBVIEW_BROWSER_COMPOSITOR_ID_H_
+#define ANDROID_WEBVIEW_BROWSER_COMPOSITOR_ID_H_
+
+namespace android_webview {
+
+struct CompositorID {
+  CompositorID();
+  CompositorID(int process_id, int routing_id);
+  CompositorID(const CompositorID& other);

[boliu, 2016/06/03 02:18:20]

if you allow copy constructor, then add the assignment operator too

[hush (inactive), 2016/06/09 22:44:53]

why? classes like content::DropData has copy constructor, but has no assignment=
overloaded.

[boliu, 2016/06/10 15:40:33]

DropData is wrong too

https://google.github.io/styleguide/cppguide.html#Copyable_Movable_Types

If you define a copy or move constructor, define the corresponding assignment
operator, and vice-versa.

Also the advice given by effective c++ fwiw

+
+  int process_id;
+  int routing_id;
+};
+
+struct CompositorIDIsDifferent {

[boliu, 2016/06/03 02:18:20]

write an actual operator? I think that should work for std::map..

[hush (inactive), 2016/06/09 22:44:53]

done.

+  // Returns false if 2 objects are equal.
+  bool operator()(const CompositorID& lhs, const CompositorID& rhs) const;
+};
+
+}  // namespace android_webview
+
+#endif  // ANDROID_WEBVIEW_BROWSER_COMPOSITOR_ID_H_