Rewire Android WebView's compositor changed signal.

android_webview/browser/browser_view_renderer.h

Index: android_webview/browser/browser_view_renderer.h
diff --git a/android_webview/browser/browser_view_renderer.h b/android_webview/browser/browser_view_renderer.h
index 56874d79b4d808381584c5cfabfea23f2f4b03cc..f7574e8e59840f6be232d716786d0ca6fe6ecc97 100644
--- a/android_webview/browser/browser_view_renderer.h
+++ b/android_webview/browser/browser_view_renderer.h
@@ -11,6 +11,7 @@
 #include <set>
 
 #include "android_webview/browser/compositor_frame_producer.h"
+#include "android_webview/browser/compositor_id.h"
 #include "android_webview/browser/parent_compositor_draw_constraints.h"
 #include "base/callback.h"
 #include "base/cancelable_callback.h"
@@ -27,6 +28,7 @@ class SkCanvas;
 class SkPicture;
 
 namespace content {
+class RenderViewHost;
 class WebContents;
 }
 
@@ -108,11 +110,12 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient,
   void TrimMemory();
 
   // SynchronousCompositorClient overrides.
-  void DidInitializeCompositor(
-      content::SynchronousCompositor* compositor) override;
-  void DidDestroyCompositor(
-      content::SynchronousCompositor* compositor) override;
-  void DidBecomeCurrent(content::SynchronousCompositor* compositor) override;
+  void DidInitializeCompositor(content::SynchronousCompositor* compositor,
+                               int process_id,
+                               int routing_id) override;
+  void DidDestroyCompositor(content::SynchronousCompositor* compositor,
+                            int process_id,
+                            int routing_id) override;
   void PostInvalidate() override;
   void DidUpdateContent() override;
   void UpdateRootLayerState(const gfx::Vector2dF& total_scroll_offset_dip,
@@ -131,6 +134,8 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient,
   void RemoveCompositorFrameConsumer(
       CompositorFrameConsumer* compositor_frame_consumer) override;
 
+  void SetActiveCompositorID(const CompositorID& compositor_id);
+
  private:
   void SetTotalRootLayerScrollOffset(const gfx::Vector2dF& new_value_dip);
   bool CanOnDraw();
@@ -160,10 +165,16 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient,
 
   // The current compositor that's owned by the current RVH.
   content::SynchronousCompositor* compositor_;
+  // The process id and routing id of the most recent RVH according to
+  // RVHChanged.
+  CompositorID compositor_id_;
   // A map from compositor's per-WebView unique ID to the compositor's raw
   // pointer. A raw pointer here is fine because the entry will be erased when
   // a compositor is destroyed.
-  std::map<size_t, content::SynchronousCompositor*> compositor_map_;
+  std::map<CompositorID,
+           content::SynchronousCompositor*,
+           CompositorIDComparator>
+      compositor_map_;
 
   bool is_paused_;
   bool view_visible_;
@@ -200,8 +211,6 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient,
   // TODO(miletus): Make overscroll_rounding_error_ a gfx::ScrollOffset.
   gfx::Vector2dF overscroll_rounding_error_;
 
-  uint32_t next_compositor_id_;
-
   ParentCompositorDrawConstraints external_draw_constraints_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserViewRenderer);