sync compositor: Merge input path with chrome

Use chrome's async input delivery path in Android WebView. See bug
for potential incompatibility risk. Existing code path is not removed
in case compatibility is an issue.

Refactor out ui::SynchronousInputHandlerProxy parts from
InputHandlerManagerClient into a separate interface so that sync
compositor can use SynchronousInputHandlerProxy even without
routing input synchronously. Then just stop filtering input events in
sync compositor, hook up overscroll, and everything just works.

Tests:
testNoSpuriousOverScrolls requires synchronous input to maintain
the property that a single scroll call happens. Asynchronously the
test is not valid
AwContents.zoomIn is no longer synchronous which breaks
testPinchZoomUpdatesScrollRangeSynchronously. Can fix this
independently if this becomes a problem later.

BUG=545628

Review URL: https://codereview.chromium.org/1620053002

Cr-Commit-Position: refs/heads/master@{#380563}

1 files changed, 15 insertions, 5 deletions

diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 202c5f9..b1b76c9 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -1177,10 +1177,13 @@ void RenderThreadImpl::InitializeCompositorThread() {
 #if defined(OS_ANDROID)
   SynchronousCompositorFactory* sync_compositor_factory =
       SynchronousCompositorFactory::GetInstance();
+  const base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
   bool using_ipc_sync_compositing =
-      base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kIPCSyncCompositing);
+      cmd_line->HasSwitch(switches::kIPCSyncCompositing);
+  bool sync_input_for_sync_compositing =
+      cmd_line->HasSwitch(switches::kSyncInputForSyncCompositor);
   DCHECK(!sync_compositor_factory || !using_ipc_sync_compositing);
+  DCHECK(!sync_input_for_sync_compositing || using_ipc_sync_compositing);
 
   if (sync_compositor_factory) {
     compositor_task_runner_ =
@@ -1201,16 +1204,23 @@ void RenderThreadImpl::InitializeCompositorThread() {
                    false));
   }
 
-  InputHandlerManagerClient* input_handler_manager_client = NULL;
+  InputHandlerManagerClient* input_handler_manager_client = nullptr;
+  SynchronousInputHandlerProxyClient* synchronous_input_handler_proxy_client =
+      nullptr;
 #if defined(OS_ANDROID)
   if (using_ipc_sync_compositing) {
     sync_compositor_message_filter_ =
         new SynchronousCompositorFilter(compositor_task_runner_);
     AddFilter(sync_compositor_message_filter_.get());
-    input_handler_manager_client = sync_compositor_message_filter_.get();
+    if (sync_input_for_sync_compositing)
+      input_handler_manager_client = sync_compositor_message_filter_.get();
+    synchronous_input_handler_proxy_client =
+        sync_compositor_message_filter_.get();
   } else if (sync_compositor_factory) {
     input_handler_manager_client =
         sync_compositor_factory->GetInputHandlerManagerClient();
+    synchronous_input_handler_proxy_client =
+        sync_compositor_factory->GetSynchronousInputHandlerProxyClient();
   }
 #endif
   if (!input_handler_manager_client) {
@@ -1223,7 +1233,7 @@ void RenderThreadImpl::InitializeCompositorThread() {
   }
   input_handler_manager_.reset(new InputHandlerManager(
       compositor_task_runner_, input_handler_manager_client,
-      renderer_scheduler_.get()));
+      synchronous_input_handler_proxy_client, renderer_scheduler_.get()));
 }
 
 void RenderThreadImpl::EnsureWebKitInitialized() {