Pause requests when they’re started while the RequestManager is paused.

Pausing the request allows Glide to show a placeholder without starting the request.

instrumentation/src/androidTest/java/com/bumptech/glide/PausedRequestsTest.java

+package com.bumptech.glide;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.Context;
+import android.graphics.Color;
+import android.graphics.drawable.ColorDrawable;
+import android.support.test.InstrumentationRegistry;
+import android.widget.ImageView;
+import com.bumptech.glide.test.ConcurrencyHelper;
+import com.bumptech.glide.test.GlideApp;
+import com.bumptech.glide.test.GlideRequests;
+import com.bumptech.glide.test.ResourceIds;
+import com.bumptech.glide.test.TearDownGlide;
+import org.junit.Rule;
+import org.junit.Test;
+
+/**
+ * Tests how {@link com.bumptech.glide.request.Request}s behave when the corresponding
+ * {@link RequestManager} is paused.
+ */
+public final class PausedRequestsTest {
+  @Rule public final TearDownGlide tearDownGlide = new TearDownGlide();
+  private final ConcurrencyHelper concurrency = new ConcurrencyHelper();
+  private final Context context = InstrumentationRegistry.getTargetContext();
+
+  @SuppressWarnings("unchecked")
+  @Test
+  public void load_withPlaceHolderSet_requestsPaused_displaysPlaceholder() {
+    final ImageView imageView = new ImageView(context);
+
+    final GlideRequests requests = GlideApp.with(context);
+    concurrency.runOnMainThread(new Runnable() {
+      @Override
+      public void run() {
+        requests.pauseAllRequests();
+      }
+    });
+
+    final ColorDrawable expected = new ColorDrawable(Color.RED);
+    concurrency.runOnMainThread(
+        new Runnable() {
+          @Override
+          public void run() {
+            requests
+                .load(ResourceIds.drawable.bitmap_alias)
+                .placeholder(expected)
+                .into(imageView);
+          }
+        });
+
+    assertThat(imageView.getDrawable()).isEqualTo(expected);
+  }
+}

library/src/main/java/com/bumptech/glide/manager/RequestTracker.java

@@ -43,6 +43,7 @@ public class RequestTracker {
     if (!isPaused) {
       request.begin();
     } else {
+      request.pause();
       if (Log.isLoggable(TAG, Log.VERBOSE)) {
         Log.v(TAG, "Paused, delaying request");
       }

library/test/src/test/java/com/bumptech/glide/manager/RequestTrackerTest.java

@@ -376,6 +376,24 @@ public class RequestTrackerTest {
     verify(request).begin();
   }
 
+  @Test
+  public void runRequest_withAllRequestsPaused_pausesNewRequest() {
+    Request request = mock(Request.class);
+    tracker.pauseAllRequests();
+    tracker.runRequest(request);
+
+    verify(request).pause();
+  }
+
+  @Test
+  public void runRequest_withRequestsPaused_pausesNewRequest() {
+    Request request = mock(Request.class);
+    tracker.pauseRequests();
+    tracker.runRequest(request);
+
+    verify(request).pause();
+  }
+
   private class ClearAndRemoveRequest implements Answer<Void> {
 
     private final Request toRemove;