Adaptively throttle texture uploads

cc/CCLayerTreeHost.cpp

Index: cc/CCLayerTreeHost.cpp
diff --git a/cc/CCLayerTreeHost.cpp b/cc/CCLayerTreeHost.cpp
index 18786f52b4d8d263bdd91820ce425a5cf7dc8cb4..5d3127d423c6509be89c5b81f4b3ccd6884a4814 100644
--- a/cc/CCLayerTreeHost.cpp
+++ b/cc/CCLayerTreeHost.cpp
@@ -68,6 +68,7 @@ CCLayerTreeHost::CCLayerTreeHost(CCLayerTreeHostClient* client, const CCLayerTre
     , m_triggerIdleUpdates(true)
     , m_backgroundColor(SK_ColorWHITE)
     , m_hasTransparentBackground(false)
+    , m_maxPartialTextureUpdates(0)
     , m_partialTextureUpdateRequests(0)
 {
     ASSERT(CCProxy::isMainThread());
@@ -119,9 +120,6 @@ void CCLayerTreeHost::initializeRenderer()
     // Update m_settings based on capabilities that we got back from the renderer.
     m_settings.acceleratePainting = m_proxy->rendererCapabilities().usingAcceleratedPainting;
 
-    // Update m_settings based on partial update capability.
-    m_settings.maxPartialTextureUpdates = min(m_settings.maxPartialTextureUpdates, m_proxy->maxPartialTextureUpdates());
-
     m_contentsTextureManager = CCPrioritizedTextureManager::create(0, m_proxy->rendererCapabilities().maxTextureSize, CCRenderer::ContentPool);
     m_surfaceMemoryPlaceholder = m_contentsTextureManager->createTexture(IntSize(), GraphicsContext3D::RGBA);
 
@@ -451,7 +449,7 @@ bool CCLayerTreeHost::initializeRendererIfNeeded()
     return true;
 }
 
-void CCLayerTreeHost::updateLayers(CCTextureUpdateQueue& queue, size_t memoryAllocationLimitBytes)
+void CCLayerTreeHost::updateLayers(CCTextureUpdateQueue& queue, size_t memoryAllocationLimitBytes, size_t maxPartialTextureUpdates)
 {
     ASSERT(m_rendererInitialized);
     ASSERT(memoryAllocationLimitBytes);
@@ -464,7 +462,7 @@ void CCLayerTreeHost::updateLayers(CCTextureUpdateQueue& queue, size_t memoryAll
 
     m_contentsTextureManager->setMaxMemoryLimitBytes(memoryAllocationLimitBytes);
 
-    updateLayers(rootLayer(), queue);
+    updateLayers(rootLayer(), queue, maxPartialTextureUpdates);
 }
 
 static void setScale(LayerChromium* layer, float deviceScaleFactor, float pageScaleFactor)
@@ -492,7 +490,7 @@ static void updateLayerScale(LayerChromium* layer, float deviceScaleFactor, floa
         updateLayerScale(children[i].get(), deviceScaleFactor, pageScaleFactor);
 }
 
-void CCLayerTreeHost::updateLayers(LayerChromium* rootLayer, CCTextureUpdateQueue& queue)
+void CCLayerTreeHost::updateLayers(LayerChromium* rootLayer, CCTextureUpdateQueue& queue, size_t maxPartialTextureUpdates)
 {
     TRACE_EVENT0("cc", "CCLayerTreeHost::updateLayers");
 
@@ -508,6 +506,7 @@ void CCLayerTreeHost::updateLayers(LayerChromium* rootLayer, CCTextureUpdateQueu
 
     // Reset partial texture update requests.
     m_partialTextureUpdateRequests = 0;
+    m_maxPartialTextureUpdates = std::min(m_settings.maxPartialTextureUpdates, maxPartialTextureUpdates);
 
     bool needMoreUpdates = paintLayerContents(updateList, queue);
     if (m_triggerIdleUpdates && needMoreUpdates)
@@ -716,7 +715,7 @@ bool CCLayerTreeHost::bufferedUpdates()
 
 bool CCLayerTreeHost::requestPartialTextureUpdate()
 {
-    if (m_partialTextureUpdateRequests >= m_settings.maxPartialTextureUpdates)
+    if (m_partialTextureUpdateRequests >= m_maxPartialTextureUpdates)
         return false;
 
     m_partialTextureUpdateRequests++;