cc: Free gpu resources when we are invisible or TM is oom.

cc/resources/gpu_rasterizer.cc

Index: cc/resources/gpu_rasterizer.cc
diff --git a/cc/resources/gpu_rasterizer.cc b/cc/resources/gpu_rasterizer.cc
index 6e318edabbe80a2c670eef3baf96abf9dd36d990..5657a7fd62c3be49dd0596348c2413e33de8a3dc 100644
--- a/cc/resources/gpu_rasterizer.cc
+++ b/cc/resources/gpu_rasterizer.cc
@@ -191,4 +191,10 @@ void GpuRasterizer::AddToMultiPictureDraw(const Tile* tile,
   multi_picture_draw_.add(sk_surface->getCanvas(), picture.get());
 }
 
+void GpuRasterizer::ClearCache() {
+  GrContext* gr_context = GetContextProvider(false)->GrContext();

[vmiura, 2015/03/19 21:20:35]

For threaded GPU raster we need to take a lock on the worker context.

https://code.google.com/p/chromium/codesearch#chromium/src/cc/resources/gpu_t...

    ContextProvider* context_provider = rasterizer_->resource_provider()
                                            ->output_surface()
                                            ->worker_context_provider();

    // The context lock must be held while accessing the context on a
    // worker thread.
    base::AutoLock context_lock(*context_provider->GetLock());

    // Allow context to bind to current thread.
    context_provider->DetachFromThread();

    // Rasterize source into resource.
    reduce cache limit here

    // Barrier to sync worker context output to cc context.
    context_provider->ContextGL()->OrderingBarrierCHROMIUM();

    // Allow context to bind to other threads.
    context_provider->DetachFromThread();

[sohanjg, 2015/03/23 10:34:38]

Done.

+  DCHECK(gr_context);
+  gr_context->setResourceCacheLimits(0, 0);
+}
+
 }  // namespace cc