Allow using a larger-than-necessary texture as cached render pass backing

When moving a composited layer around the screen that requires a render pass,
it's not all that unusual for the required size to be slightly different from
frame to frame. This lets us use an oversized texture as the framebuffer
attachment.

BUG=161868


Review URL: https://chromiumcodereview.appspot.com/11420079

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@173112 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 12 insertions, 2 deletions

diff --git a/cc/direct_renderer.cc b/cc/direct_renderer.cc
index 0b2d74b..3460160 100644
--- a/cc/direct_renderer.cc
+++ b/cc/direct_renderer.cc
@@ -113,6 +113,11 @@ DirectRenderer::~DirectRenderer()
 {
 }
 
+void DirectRenderer::setEnlargePassTextureAmountForTesting(gfx::Vector2d amount)
+{
+    m_enlargePassTextureAmount = amount;
+}
+
 void DirectRenderer::decideRenderPassAllocationsForFrame(const RenderPassList& renderPassesInDrawOrder)
 {
     base::hash_map<RenderPass::Id, const RenderPass*> renderPassesInFrame;
@@ -134,7 +139,9 @@ void DirectRenderer::decideRenderPassAllocationsForFrame(const RenderPassList& r
         CachedResource* texture = passIterator->second;
         DCHECK(texture);
 
-        if (texture->id() && (texture->size() != requiredSize || texture->format() != requiredFormat))
+        bool sizeAppropriate = texture->size().width() >= requiredSize.width() &&
+                               texture->size().height() >= requiredSize.height();
+        if (texture->id() && (!sizeAppropriate || texture->format() != requiredFormat))
             texture->Free();
     }
 
@@ -267,7 +274,10 @@ bool DirectRenderer::useRenderPass(DrawingFrame& frame, const RenderPass* render
 
     CachedResource* texture = m_renderPassTextures.get(renderPass->id);
     DCHECK(texture);
-    if (!texture->id() && !texture->Allocate(Renderer::ImplPool, renderPassTextureSize(renderPass), renderPassTextureFormat(renderPass), ResourceProvider::TextureUsageFramebuffer))
+
+    gfx::Size size = renderPassTextureSize(renderPass);
+    size.Enlarge(m_enlargePassTextureAmount.x(), m_enlargePassTextureAmount.y());
+    if (!texture->id() && !texture->Allocate(Renderer::ImplPool, size, renderPassTextureFormat(renderPass), ResourceProvider::TextureUsageFramebuffer))
         return false;
 
     return bindFramebufferToTexture(frame, texture, renderPass->output_rect);