[Android] Expose method for UI to force composites

Allow the ContentViewRenderView to request composites if UX components require it.

BUG=387177

Review URL: https://codereview.chromium.org/504553002

Cr-Commit-Position: refs/heads/master@{#291982}

content/browser/android/content_view_render_view.cc

@@ -120,6 +120,12 @@ void ContentViewRenderView::SurfaceChanged(JNIEnv* env, jobject obj,
 void ContentViewRenderView::SetOverlayVideoMode(
     JNIEnv* env, jobject obj, bool enabled) {
   compositor_->SetHasTransparentBackground(enabled);
+  SetNeedsComposite(env, obj);
+}
+
+void ContentViewRenderView::SetNeedsComposite(JNIEnv* env, jobject obj) {
+  if (compositor_)
+    compositor_->SetNeedsComposite();
 }
 
 void ContentViewRenderView::Layout() {

content/browser/android/content_view_render_view.h

@@ -41,6 +41,7 @@ class ContentViewRenderView : public CompositorClient {
                       jint format, jint width, jint height, jobject surface);
   jboolean Composite(JNIEnv* env, jobject obj);
   void SetOverlayVideoMode(JNIEnv* env, jobject obj, bool enabled);
+  void SetNeedsComposite(JNIEnv* env, jobject obj);
 
   // CompositorClient implementation
   virtual void Layout() OVERRIDE;

content/public/android/java/src/org/chromium/content/browser/ContentViewRenderView.java

@@ -147,6 +147,15 @@ public class ContentViewRenderView extends FrameLayout {
         }
     }
 
+    /**
+     * Trigger a redraw of the compositor.  This is only needed if the UI changes something that
+     * does not trigger a redraw itself by updating the layer tree.
+     */
+    public void setNeedsComposite() {
+        if (mNativeContentViewRenderView == 0) return;
+        nativeSetNeedsComposite(mNativeContentViewRenderView);
+    }
+
     /**
      * This method should be subclassed to provide actions to be performed once the view is ready to
      * render.
@@ -216,4 +225,5 @@ public class ContentViewRenderView extends FrameLayout {
             int format, int width, int height, Surface surface);
     private native void nativeSetOverlayVideoMode(long nativeContentViewRenderView,
             boolean enabled);
+    private native void nativeSetNeedsComposite(long nativeContentViewRenderView);
 }