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

cc/resources/gpu_rasterizer.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/resources/gpu_rasterizer.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/metrics/histogram.h"
@@ skipping 173 matching lines @@
   canvas->save();
   tile->raster_source()->PlaybackToCanvas(canvas.get(), tile->content_rect(),
                                           tile->contents_scale());
   canvas->restore();
 
   // Add the canvas and recorded picture to |multi_picture_draw_|.
   skia::RefPtr<SkPicture> picture = skia::AdoptRef(recorder.endRecording());
   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