Add RemoteInputConnectionImpl#finishComposingTextFromImm()

This is a preparation CL to make InputConnection tasks cancellable.

Currently

  RemoteInputConnectionImpl#finishComposingText()

is the only method that can be called by both RemoteInputConnection as
a Binder call and InputMethodManager as a direct invocation.  This is
not convenient because a common header data structure is going to be
added to every IPC defined in IInputContext in order to implement
InputConnection task cancelation.

Thus, this CL introduces

  RemoteInputConnectionImpl#finishComposingTextFromImm()

to decouple this code path from subsequent CLs.

There should be no observable behavior change yet in this CL.

Bug: 195115071
Test: presubmit
Change-Id: I07290af2595c7a556cb5daa8a4c0f9c4a7daa49c

core/java/android/view/inputmethod/InputMethodManager.java

@@ -696,7 +696,7 @@ public final class InputMethodManager {
         @Override
         public void finishComposingText() {
             if (mServedInputConnection != null) {
-                mServedInputConnection.finishComposingText();
+                mServedInputConnection.finishComposingTextFromImm();
             }
         }
 
@@ -919,7 +919,7 @@ public final class InputMethodManager {
                             mRestartOnNextWindowFocus = true;
                             // Note that finishComposingText() is allowed to run
                             // even when we are not active.
-                            mFallbackInputConnection.finishComposingText();
+                            mFallbackInputConnection.finishComposingTextFromImm();
                         }
                         // Check focus again in case that "onWindowFocus" is called before
                         // handling this message.

core/java/com/android/internal/inputmethod/RemoteInputConnectionImpl.java

@@ -430,6 +430,34 @@ public final class RemoteInputConnectionImpl extends IInputContext.Stub {
         });
     }
 
+    /**
+     * Dispatches {@link InputConnection#finishComposingText()}.
+     *
+     * <p>This method is intended to be called only from {@link InputMethodManager}.</p>
+     */
+    public void finishComposingTextFromImm() {
+        dispatchWithTracing("finishComposingTextFromImm", () -> {
+            if (isFinished()) {
+                // In this case, #finishComposingText() is guaranteed to be called already.
+                // There should be no negative impact if we ignore this call silently.
+                if (DEBUG) {
+                    Log.w(TAG, "Bug 35301295: Redundant finishComposingTextFromImm.");
+                }
+                return;
+            }
+            InputConnection ic = getInputConnection();
+            // Note we do NOT check isActive() here, because this is safe
+            // for an IME to call at any time, and we need to allow it
+            // through to clean up our state after the IME has switched to
+            // another client.
+            if (ic == null) {
+                Log.w(TAG, "finishComposingTextFromImm on inactive InputConnection");
+                return;
+            }
+            ic.finishComposingText();
+        });
+    }
+
     @Override
     public void finishComposingText() {
         dispatchWithTracing("finishComposingText", () -> {