[Chromecast] Decouple WebContents life cycle from StartParams.

It's possible for a new Intent with the same WebContents, but
different values for mutable parameters like enableTouchInput.
When this happens, the WebContents would be reinitialized, which
breaks an assertion in WebContentsImpl.

By storing the WebContents in a separate Controller, we allow it
to persist across a reactivation of mStartParamsState where the
new WebContents is equal to the previous instance.

Bug: internal b/120089917
Test: cast_shell_junit_tests
Change-Id: Id9d58b577a887ffff4002ec6fcde578a71752b1f
Reviewed-on: https://chromium-review.googlesource.com/c/1352077
Commit-Queue: Simeon Anfinrud <sanfin@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611808}

chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastWebContentsSurfaceHelper.java

@@ -112,8 +112,10 @@ class CastWebContentsSurfaceHelper {
                 (WebContents webContents) -> MediaSessionImpl.fromWebContents(webContents);
 
         Observable<Uri> uriState = mStartParamsState.map(params -> params.uri);
-        Observable<WebContents> webContentsState =
-                mStartParamsState.map(params -> params.webContents);
+        Controller<WebContents> webContentsState = new Controller<>();
+        mStartParamsState.map(params -> params.webContents)
+                .subscribe(Observers.onEnter(webContentsState::set));
+        mCreatedState.subscribe(Observers.onExit(x -> webContentsState.reset()));
 
         // Receive broadcasts indicating the screen turned off while we have active WebContents.
         uriState.subscribe((Uri uri) -> {
@@ -121,6 +123,7 @@ class CastWebContentsSurfaceHelper {
             filter.addAction(CastIntents.ACTION_SCREEN_OFF);
             return new LocalBroadcastReceiverScope(filter, (Intent intent) -> {
                 mStartParamsState.reset();
+                webContentsState.reset();
                 maybeFinishLater(handler, () -> finishCallback.accept(uri));
             });
         });
@@ -137,6 +140,7 @@ class CastWebContentsSurfaceHelper {
                     return;
                 }
                 mStartParamsState.reset();
+                webContentsState.reset();
                 maybeFinishLater(handler, () -> finishCallback.accept(uri));
             });
         });

chromecast/browser/android/junit/src/org/chromium/chromecast/shell/CastWebContentsSurfaceHelperTest.java

@@ -11,6 +11,7 @@ import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -168,6 +169,28 @@ public class CastWebContentsSurfaceHelperTest {
         verify(mWebContentsView).open(webContents2);
     }
 
+    @Test
+    public void testDoesNotRestartWebContentsIfNewStartParamsHasSameWebContents() {
+        WebContents webContents = mock(WebContents.class);
+        // Create two StartParams that have the same WebContents but different values.
+        StartParams params1 = new StartParamsBuilder()
+                                      .withId("1")
+                                      .withWebContents(webContents)
+                                      .enableTouchInput(false)
+                                      .build();
+        StartParams params2 = new StartParamsBuilder()
+                                      .withId("1")
+                                      .withWebContents(webContents)
+                                      .enableTouchInput(true)
+                                      .build();
+        Scope scope = mock(Scope.class);
+        when(mWebContentsView.open(webContents)).thenReturn(scope);
+        mSurfaceHelper.onNewStartParams(params1);
+        // The second StartParams has the same WebContents, so we shouldn't open the scopes again.
+        mSurfaceHelper.onNewStartParams(params2);
+        verify(mWebContentsView, times(1)).open(webContents);
+    }
+
     @Test
     public void testIsTouchInputEnabled() {
         assertFalse(mSurfaceHelper.isTouchInputEnabled());