Add hints for potential overlay promotion on android.

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index 1be0b13564fc2774c44982e9f0bd6b967f5b2138..1483bad9dfb9c5350bf1c70526057a583ff60abb 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -236,6 +236,10 @@ ResourceProvider::Resource::Resource(GLuint texture_id,
       read_lock_fences_enabled(false),
       has_shared_bitmap_id(false),
       is_overlay_candidate(false),
+#if defined(OS_ANDROID)
+      is_backed_by_surface_texture(false),
+      wants_promotion_hint(false),
+#endif
       read_lock_fence(nullptr),
       size(size),
       origin(origin),
@@ -248,7 +252,8 @@ ResourceProvider::Resource::Resource(GLuint texture_id,
       type(type),
       usage(gfx::BufferUsage::GPU_READ_CPU_READ_WRITE),
       format(format),
-      shared_bitmap(nullptr) {}
+      shared_bitmap(nullptr) {
+}
 
 ResourceProvider::Resource::Resource(uint8_t* pixels,
                                      SharedBitmap* bitmap,
@@ -272,6 +277,10 @@ ResourceProvider::Resource::Resource(uint8_t* pixels,
       read_lock_fences_enabled(false),
       has_shared_bitmap_id(!!bitmap),
       is_overlay_candidate(false),
+#if defined(OS_ANDROID)
+      is_backed_by_surface_texture(false),
+      wants_promotion_hint(false),
+#endif
       read_lock_fence(nullptr),
       size(size),
       origin(origin),
@@ -310,6 +319,10 @@ ResourceProvider::Resource::Resource(const SharedBitmapId& bitmap_id,
       read_lock_fences_enabled(false),
       has_shared_bitmap_id(true),
       is_overlay_candidate(false),
+#if defined(OS_ANDROID)
+      is_backed_by_surface_texture(false),
+      wants_promotion_hint(false),
+#endif
       read_lock_fence(nullptr),
       size(size),
       origin(origin),
@@ -322,7 +335,8 @@ ResourceProvider::Resource::Resource(const SharedBitmapId& bitmap_id,
       type(RESOURCE_TYPE_BITMAP),
       format(RGBA_8888),
       shared_bitmap_id(bitmap_id),
-      shared_bitmap(nullptr) {}
+      shared_bitmap(nullptr) {
+}
 
 ResourceProvider::Resource::Resource(Resource&& other) = default;
 
@@ -687,6 +701,11 @@ ResourceId ResourceProvider::CreateResourceFromTextureMailbox(
                  base::Owned(release_callback_impl.release()));
   resource->read_lock_fences_enabled = read_lock_fences_enabled;
   resource->is_overlay_candidate = mailbox.is_overlay_candidate();
+#if defined(OS_ANDROID)
+  resource->is_backed_by_surface_texture =
+      mailbox.is_backed_by_surface_texture();
+  resource->wants_promotion_hint = mailbox.wants_promotion_hint();
+#endif
   resource->color_space = mailbox.color_space();
 
   return id;
@@ -1051,6 +1070,13 @@ bool ResourceProvider::IsOverlayCandidate(ResourceId id) {
   return resource->is_overlay_candidate;
 }
 
+#if defined(OS_ANDROID)
+bool ResourceProvider::IsBackedBySurfaceTexture(ResourceId id) {
+  Resource* resource = GetResource(id);
+  return resource->is_backed_by_surface_texture;
+}
+#endif
+
 void ResourceProvider::UnlockForWrite(Resource* resource) {
   DCHECK(resource->locked_for_write);
   DCHECK_EQ(resource->exported_count, 0);
@@ -1538,6 +1564,10 @@ void ResourceProvider::ReceiveFromChild(
                                            it->mailbox_holder.texture_target));
       resource->read_lock_fences_enabled = it->read_lock_fences_enabled;
       resource->is_overlay_candidate = it->is_overlay_candidate;
+#if defined(OS_ANDROID)
+      resource->is_backed_by_surface_texture = it->is_backed_by_surface_texture;
+      resource->wants_promotion_hint = it->wants_promotion_hint;
+#endif
       resource->color_space = it->color_space;
     }
     resource->child_id = child;
@@ -1626,6 +1656,30 @@ void ResourceProvider::ReceiveReturnsFromParent(
   }
 }
 
+#if defined(OS_ANDROID)
+void ResourceProvider::SendPromotionHints(const ResourceIdSet& promotable_set) {
+  GLES2Interface* gl = ContextGL();
+  DCHECK(gl);
+
+  for (const auto& it : resources_) {

[piman, 2016/12/01 21:55:25]

This sounds mildly expensive to go over all resources (including tiles etc.). If
it is, maybe we can keep the wants_promotion_hint resources into a separate set.

[liberato (no reviews please), 2016/12/05 18:14:01]

Done.

+    const Resource& resource = it.second;
+    // The resource must care about promotion hints.
+    if (!resource.wants_promotion_hint)
+      continue;
+
+    // Insist that this is backed by a GPU texture.
+    if (!IsGpuResourceType(resource.type))
+      continue;
+
+    // TODO(liberato): I'm unsure why we can assume that |gl_id| is set yet
+    // without using a read lock.

[piman, 2016/12/01 21:55:25]

I don't think you can, actually, gl_id is set (and the mailbox bound) on the
first LockForRead.
I think you want to Lock/UnlockForRead() around the GL call.

[liberato (no reviews please), 2016/12/05 18:14:01]

Done.

+    DCHECK(resource.gl_id);
+    // gl->SetStreamTexturePromotionHintCHROMIUM(resource.gl_id,

[piman, 2016/12/01 21:55:25]

Do you expect we'll be doing a lot of these every frame? If so, I would
recommend adding a "multi" call where you would pass an array of gl textures.

[liberato (no reviews please), 2016/12/05 18:14:01]

good question.  it'll be one per video element that gets to the compositor,
which think requires it to be on screen or near it.  at least, i see hints stop
flowing by when i scroll an element off screen.

so, it's probably not too many.

+    // promotable_set.count(it->first) > 0);
+  }
+}
+#endif
+
 void ResourceProvider::CreateMailboxAndBindResource(
     gpu::gles2::GLES2Interface* gl,
     Resource* resource) {
@@ -1665,6 +1719,10 @@ void ResourceProvider::TransferResource(Resource* source,
   resource->size = source->size;
   resource->read_lock_fences_enabled = source->read_lock_fences_enabled;
   resource->is_overlay_candidate = source->is_overlay_candidate;
+#if defined(OS_ANDROID)
+  resource->is_backed_by_surface_texture = source->is_backed_by_surface_texture;
+  resource->wants_promotion_hint = source->wants_promotion_hint;
+#endif
   resource->color_space = source->color_space;
 
   if (source->type == RESOURCE_TYPE_BITMAP) {