cc: Make the scheduler compositeAndReadback flow not race with WAITING_FOR_FIRST_DRAW

cc/layer_tree_host_unittest.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layer_tree_host.h"
 
 #include "base/synchronization/lock.h"
 #include "cc/content_layer.h"
 #include "cc/content_layer_client.h"
 #include "cc/layer_impl.h"
@@ skipping 260 matching lines @@
 private:
     int m_numCommits;
     int m_numDraws;
 };
 
 TEST_F(LayerTreeHostTestSetNeedsRedraw, runMultiThread)
 {
     runTest(true);
 }
 
+class LayerTreeHostTestCompositeAndReadback : public LayerTreeHostTest {
+public:
+    LayerTreeHostTestCompositeAndReadback()
+        : m_numCommits(0)
+    {
+    }
+
+    virtual void beginTest() OVERRIDE
+    {
+        postSetNeedsCommitToMainThread();
+    }
+
+    virtual void didCommit() OVERRIDE
+    {
+        m_numCommits++;
+        if (m_numCommits == 1) {
+            char pixels[4];
+            m_layerTreeHost->compositeAndReadback(static_cast<void*>(&pixels), gfx::Rect(0, 0, 1, 1));
+        } else if (m_numCommits == 2) {
+            // This is inside the readback. We should get another commit after it.
+        } else if (m_numCommits == 3) {
+            endTest();
+        } else {
+          NOTREACHED();
+        }
+    }
+
+    virtual void afterTest() OVERRIDE
+    {
+    }
+
+private:
+    int m_numCommits;
+};
+
+TEST_F(LayerTreeHostTestCompositeAndReadback, runMultiThread)
+{
+    runTest(true);
+}
+
+class LayerTreeHostTestCompositeAndReadbackBeforePreviousCommitDraws : public LayerTreeHostTest {
+public:
+    LayerTreeHostTestCompositeAndReadbackBeforePreviousCommitDraws()
+        : m_numCommits(0)
+    {
+    }
+
+    virtual void beginTest() OVERRIDE
+    {
+        postSetNeedsCommitToMainThread();
+    }
+
+    virtual void didCommit() OVERRIDE
+    {
+        m_numCommits++;
+        if (m_numCommits == 1) {
+            m_layerTreeHost->setNeedsCommit();
+        } else if (m_numCommits == 2) {
+            char pixels[4];
+            m_layerTreeHost->compositeAndReadback(static_cast<void*>(&pixels), gfx::Rect(0, 0, 1, 1));
+        } else if (m_numCommits == 3) {
+            // This is inside the readback. We should get another commit after it.
+        } else if (m_numCommits == 4) {
+            endTest();
+        } else {
+          NOTREACHED();
+        }
+    }
+
+    virtual void afterTest() OVERRIDE
+    {
+    }
+
+private:
+    int m_numCommits;
+};
+
+TEST_F(LayerTreeHostTestCompositeAndReadbackBeforePreviousCommitDraws, runMultiThread)
+{
+    runTest(true);
+}
+
 // If the layerTreeHost says it can't draw, then we should not try to draw.
 class LayerTreeHostTestCanDrawBlocksDrawing : public LayerTreeHostTest {
 public:
     LayerTreeHostTestCanDrawBlocksDrawing()
         : m_numCommits(0)
         , m_done(false)
     {
     }
 
     virtual void beginTest() OVERRIDE
@@ skipping 23 matching lines @@
     virtual void didCommit() OVERRIDE
     {
         m_numCommits++;
         if (m_numCommits == 1) {
             // Make the viewport empty so the host says it can't draw.
             m_layerTreeHost->setViewportSize(gfx::Size(0, 0), gfx::Size(0, 0));
         } else if (m_numCommits == 2) {
             char pixels[4];
             m_layerTreeHost->compositeAndReadback(static_cast<void*>(&pixels), gfx::Rect(0, 0, 1, 1));
         } else if (m_numCommits == 3) {
-            postSetNeedsRedrawToMainThread();
-            postSetNeedsCommitToMainThread();
-        } else if (m_numCommits == 4) {
             // Let it draw so we go idle and end the test.
             m_layerTreeHost->setViewportSize(gfx::Size(1, 1), gfx::Size(1, 1));
             m_done = true;
             endTest();
         }
     }
 
     virtual void afterTest() OVERRIDE
     {
     }
@@ skipping 3076 matching lines @@
     LayerTreeSettings settings;
     settings.maxPartialTextureUpdates = 4;
 
     scoped_ptr<LayerTreeHost> host = LayerTreeHost::create(&client, settings, scoped_ptr<Thread>());
     EXPECT_TRUE(host->initializeRendererIfNeeded());
     EXPECT_EQ(0u, host->settings().maxPartialTextureUpdates);
 }
 
 }  // namespace
 }  // namespace cc