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..34e0f2ee35d737b2107adb9f790167863df4b41a 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"
@@ -18,6 +19,7 @@
 #include "base/trace_event/trace_event.h"
 #include "content/public/browser/android/synchronous_compositor.h"
 #include "content/public/browser/android/synchronous_compositor_client.h"
+#include "content/public/browser/web_contents_observer.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size_f.h"
@@ -27,6 +29,7 @@ class SkCanvas;
 class SkPicture;
 
 namespace content {
+class RenderViewHost;
 class WebContents;
 }
 
@@ -39,6 +42,7 @@ class CompositorFrameConsumer;
 // Interface for all the WebView-specific content rendering operations.
 // Provides software and hardware rendering and the Capture Picture API.
 class BrowserViewRenderer : public content::SynchronousCompositorClient,
+                            public content::WebContentsObserver,
                             public CompositorFrameProducer {
  public:
   static void CalculateTileMemoryPolicy();
@@ -46,6 +50,7 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient,
       content::WebContents* web_contents);
 
   BrowserViewRenderer(
+      content::WebContents* web_contents,
       BrowserViewRendererClient* client,
       const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner);
 
@@ -108,11 +113,12 @@ 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,
@@ -125,6 +131,10 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient,
                      const gfx::Vector2dF& latest_overscroll_delta,
                      const gfx::Vector2dF& current_fling_velocity) override;
 
+  // content::WebContentsObserver overrides
+  void RenderViewHostChanged(content::RenderViewHost* old_host,
+                             content::RenderViewHost* new_host) override;
+
   // CompositorFrameProducer overrides
   void OnParentDrawConstraintsUpdated(
       CompositorFrameConsumer* compositor_frame_consumer) override;
@@ -159,11 +169,15 @@ class BrowserViewRenderer : public content::SynchronousCompositorClient,
   std::set<CompositorFrameConsumer*> compositor_frame_consumers_;
 
   // The current compositor that's owned by the current RVH.
+  // When compositor_ != nullptr, compositor_id_ is the id of compositor_.
+  // When compositor_ == nullptr, compositor_id_ is the id of the future
+  // compositor.
   content::SynchronousCompositor* compositor_;
+  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*> compositor_map_;
 
   bool is_paused_;
   bool view_visible_;
@@ -200,8 +214,6 @@ 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);