aw: Ensure fallback tick unsets |block_invalidates_|

android_webview/browser/browser_view_renderer.cc

Index: android_webview/browser/browser_view_renderer.cc
diff --git a/android_webview/browser/browser_view_renderer.cc b/android_webview/browser/browser_view_renderer.cc
index 93ab0a8073e4d126effe033d8a0b0181d9d72ff8..7a3c703b7848ef18bbc00c5c3b6d5d4cf9fffaa6 100644
--- a/android_webview/browser/browser_view_renderer.cc
+++ b/android_webview/browser/browser_view_renderer.cc
@@ -717,6 +717,9 @@ void BrowserViewRenderer::PostFallbackTick() {
         FROM_HERE,
         fallback_tick_fired_.callback(),
         base::TimeDelta::FromMilliseconds(kFallbackTickTimeoutInMilliseconds));
+  } else {
+    // Pretend we just composited to unblock further invalidates.
+    DidComposite();
   }
 }
 
@@ -729,8 +732,12 @@ void BrowserViewRenderer::FallbackTickFired() {
   // This should only be called if OnDraw or DrawGL did not come in time, which
   // means block_invalidates_ must still be true.
   DCHECK(block_invalidates_);
-  if (compositor_needs_continuous_invalidate_ && compositor_)
+  if (compositor_needs_continuous_invalidate_ && compositor_) {
     ForceFakeCompositeSW();
+  } else {
+    // Pretend we just composited to unblock further invalidates.
+    DidComposite();
+  }
 }
 
 void BrowserViewRenderer::ForceFakeCompositeSW() {