Fixes a bug when the framebuffer is cleared with invalid scissor rect

cc/direct_renderer.cc

Index: cc/direct_renderer.cc
diff --git a/cc/direct_renderer.cc b/cc/direct_renderer.cc
index 31f48e5f935be6f4e1fd88d49c5b8824067c417a..8ee56d1f2f5dcc71951a2d6793a5320481980ae8 100644
--- a/cc/direct_renderer.cc
+++ b/cc/direct_renderer.cc
@@ -144,6 +144,8 @@ void DirectRenderer::decideRenderPassAllocationsForFrame(const RenderPassList& r
                                texture->size().height() >= requiredSize.height();
         if (texture->id() && (!sizeAppropriate || texture->format() != requiredFormat))
             texture->Free();
+        else if (texture->size() != requiredSize)

[danakj, 2013/01/24 23:38:04]

What happens if you texture->setIsComplete(false) here instead?

+            texture->setNeedsFullClear(true);

[danakj, 2013/01/24 23:23:18]

Doesn't this clear the whole texture every frame once your surface shrinks down
by 1px?

[danakj, 2013/01/24 23:39:25]

Before it would have reallocated a new texture of the right size, and not
cleared it every frame.

     }
 
     // Delete RenderPass textures from the previous frame that will not be used again.
@@ -240,8 +242,16 @@ void DirectRenderer::drawRenderPass(DrawingFrame& frame, const RenderPass* rende
         setScissorTestRect(moveScissorToWindowSpace(frame, renderPassScissor));
     }
 
-    if (frame.currentRenderPass != frame.rootRenderPass || m_client->shouldClearRootRenderPass())
-        clearFramebuffer(frame);
+    bool isRootPass = frame.currentRenderPass == frame.rootRenderPass;
+    if (!isRootPass || m_client->shouldClearRootRenderPass()) {
+        CachedResource* texture = m_renderPassTextures.get(frame.currentRenderPass->id);
+        DCHECK(texture);
+        bool fullClear = false;
+        if (!isRootPass)
+            fullClear = texture->needsFullClear();
+        clearFramebuffer(frame, fullClear);
+        texture->setNeedsFullClear(false);
+    }
 
     const QuadList& quadList = renderPass->quad_list;
     for (QuadList::constBackToFrontIterator it = quadList.backToFrontBegin(); it != quadList.backToFrontEnd(); ++it) {