Re-land "cc: Remove TextureLayer::SetTextureId and TextureLayer::WillModifyTexture"

Reason for re-land: Change was found not guilty; charges were dropped.

> Revert 261380 "cc: Remove TextureLayer::SetTextureId and Texture..."
> 
> [Reason for revert: failure in WindowUtilTest.RecreateLayers
>  in test suite wm_core_unittests
>  on bot Linux ChromiumOS Tests (dbg)(1) Build]
> 
> > cc: Remove TextureLayer::SetTextureId and TextureLayer::WillModifyTexture
> > 
> > These are not used anymore except for clearing the client-provided texture, so
> > this removes 1 of 4 TextureLayer paths, and simplifies externally-exposed state.
> > 
> > BUG=337922
> > 
> > Review URL: https://codereview.chromium.org/213743005
> 
> TBR=piman@chromium.org
> 
> Review URL: https://codereview.chromium.org/224153003

TBR=nick@chromium.org

Review URL: https://codereview.chromium.org/224363003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261490 0039d316-1c4b-4281-b951-d872f2087c98

cc/layers/texture_layer.cc

@@ -35,7 +35,7 @@ TextureLayer::TextureLayer(TextureLayerClient* client, bool uses_mailbox)
       premultiplied_alpha_(true),
       blend_background_color_(false),
       rate_limit_context_(false),
-      content_committed_(false),
+      impl_may_draw_client_data_(false),
       texture_id_(0),
       needs_set_mailbox_(false) {
   vertex_opacity_[0] = 1.0f;
@@ -51,10 +51,24 @@ void TextureLayer::ClearClient() {
   if (rate_limit_context_ && client_ && layer_tree_host())
     layer_tree_host()->StopRateLimiter();
   client_ = NULL;
-  if (uses_mailbox_)
+  ClearTexture();
+}
+
+void TextureLayer::ClearTexture() {
+  if (uses_mailbox_) {
     SetTextureMailbox(TextureMailbox(), scoped_ptr<SingleReleaseCallback>());
-  else
-    SetTextureId(0);
+  } else if (texture_id_) {
+    if (impl_may_draw_client_data_) {
+      DCHECK(layer_tree_host());
+      layer_tree_host()->AcquireLayerTextures();
+      impl_may_draw_client_data_ = false;
+    }
+    texture_id_ = 0;
+    SetNeedsCommit();
+    // The texture id needs to be removed from the active tree before the
+    // commit is called complete.
+    SetNextCommitWaitsForActivation();
+  }
 }
 
 scoped_ptr<LayerImpl> TextureLayer::CreateLayerImpl(LayerTreeImpl* tree_impl) {
@@ -119,19 +133,6 @@ void TextureLayer::SetRateLimitContext(bool rate_limit) {
   rate_limit_context_ = rate_limit;
 }
 
-void TextureLayer::SetTextureId(unsigned id) {
-  DCHECK(!uses_mailbox_);
-  if (texture_id_ == id)
-    return;
-  if (texture_id_ && layer_tree_host())
-    layer_tree_host()->AcquireLayerTextures();
-  texture_id_ = id;
-  SetNeedsCommit();
-  // The texture id needs to be removed from the active tree before the
-  // commit is called complete.
-  SetNextCommitWaitsForActivation();
-}
-
 void TextureLayer::SetTextureMailboxInternal(
     const TextureMailbox& mailbox,
     scoped_ptr<SingleReleaseCallback> release_callback,
@@ -190,14 +191,6 @@ void TextureLayer::SetTextureMailboxWithoutReleaseCallback(
       mailbox, release.Pass(), requires_commit, allow_mailbox_reuse);
 }
 
-void TextureLayer::WillModifyTexture() {
-  if (!uses_mailbox_ && layer_tree_host() && (DrawsContent() ||
-      content_committed_)) {
-    layer_tree_host()->AcquireLayerTextures();
-    content_committed_ = false;
-  }
-}
-
 void TextureLayer::SetNeedsDisplayRect(const gfx::RectF& dirty_rect) {
   Layer::SetNeedsDisplayRect(dirty_rect);
 
@@ -212,11 +205,12 @@ void TextureLayer::SetLayerTreeHost(LayerTreeHost* host) {
   }
 
   if (layer_tree_host()) {
-    if (texture_id_) {
+    if (impl_may_draw_client_data_) {
       layer_tree_host()->AcquireLayerTextures();
       // The texture id needs to be removed from the active tree before the
       // commit is called complete.
       SetNextCommitWaitsForActivation();
+      impl_may_draw_client_data_ = false;
     }
     if (rate_limit_context_ && client_)
       layer_tree_host()->StopRateLimiter();
@@ -295,7 +289,7 @@ void TextureLayer::PushPropertiesTo(LayerImpl* layer) {
     needs_set_mailbox_ = false;
   } else {
     texture_layer->SetTextureId(texture_id_);
-    content_committed_ = DrawsContent();
+    impl_may_draw_client_data_ = texture_id_ && Layer::DrawsContent();
   }
 }
 

cc/layers/texture_layer.h

@@ -90,8 +90,20 @@ class CC_EXPORT TextureLayer : public Layer {
   static scoped_refptr<TextureLayer> CreateForMailbox(
       TextureLayerClient* client);
 
+  // Resets the client, which also resets the texture. This may synchronize with
+  // the impl thread if it is currently drawing a texture from the client, that
+  // was given via TextureLayerClient::PrepareTexture. After this call it is
+  // safe to destroy that texture. Note: it doesn't synchronize for mailboxes,
+  // those can only be destroyed after the release callback has been called.
   void ClearClient();
 
+  // Resets the texture. This may synchronize with the impl thread if it is
+  // currently drawing a texture from the client, that was given via
+  // TextureLayerClient::PrepareTexture. After this call it is safe to destroy
+  // that texture. Note: it doesn't synchronize for mailboxes, those can only be
+  // destroyed after the release callback has been called.
+  void ClearTexture();
+
   virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
       OVERRIDE;
 
@@ -122,10 +134,6 @@ class CC_EXPORT TextureLayer : public Layer {
   // Requires a non-nil client.  Defaults to false.
   void SetRateLimitContext(bool rate_limit);
 
-  // Code path for plugins which supply their own texture ID.
-  // DEPRECATED. DO NOT USE.
-  void SetTextureId(unsigned texture_id);
-
   // Code path for plugins which supply their own mailbox.
   bool uses_mailbox() const { return uses_mailbox_; }
   void SetTextureMailbox(const TextureMailbox& mailbox,
@@ -137,8 +145,6 @@ class CC_EXPORT TextureLayer : public Layer {
   // TODO(danakj): Remove this when pepper doesn't need it. crbug.com/350204
   void SetTextureMailboxWithoutReleaseCallback(const TextureMailbox& mailbox);
 
-  void WillModifyTexture();
-
   virtual void SetNeedsDisplayRect(const gfx::RectF& dirty_rect) OVERRIDE;
 
   virtual void SetLayerTreeHost(LayerTreeHost* layer_tree_host) OVERRIDE;
@@ -170,7 +176,7 @@ class CC_EXPORT TextureLayer : public Layer {
   bool premultiplied_alpha_;
   bool blend_background_color_;
   bool rate_limit_context_;
-  bool content_committed_;
+  bool impl_may_draw_client_data_;
 
   unsigned texture_id_;
   scoped_ptr<TextureMailboxHolder::MainThreadReference> holder_ref_;

content/shell/renderer/test_runner/TestPlugin.cpp

@@ -222,11 +222,8 @@ bool TestPlugin::initialize(WebPluginContainer* container)
 
 void TestPlugin::destroy()
 {
-    if (m_layer.get()) {
-        m_layer->WillModifyTexture();
-        m_layer->SetTextureMailbox(cc::TextureMailbox(),
-                                   scoped_ptr<cc::SingleReleaseCallback>());
-    }
+    if (m_layer.get())
+        m_layer->ClearTexture();
     if (m_container)
         m_container->setWebLayer(0);
     m_webLayer.reset();

ui/compositor/layer.cc

@@ -458,7 +458,7 @@ void Layer::SwitchToLayer(scoped_refptr<cc::Layer> new_layer) {
   }
 
   if (texture_layer_.get())
-    texture_layer_->WillModifyTexture();
+    texture_layer_->ClearClient();
   // TODO(piman): delegated_renderer_layer_ cleanup.
 
   cc_layer_->RemoveAllChildren();

webkit/renderer/compositor_bindings/web_external_texture_layer_impl.cc

@@ -39,9 +39,7 @@ blink::WebLayer* WebExternalTextureLayerImpl::layer() { return layer_.get(); }
 
 void WebExternalTextureLayerImpl::clearTexture() {
   TextureLayer *layer = static_cast<TextureLayer*>(layer_->layer());
-  layer->WillModifyTexture();
-  layer->SetTextureMailbox(cc::TextureMailbox(),
-                           scoped_ptr<cc::SingleReleaseCallback>());
+  layer->ClearTexture();
 }
 
 void WebExternalTextureLayerImpl::setOpaque(bool opaque) {