Add PERSISTENT_MAP usage for GpuMemoryBuffers.

content/browser/gpu/browser_gpu_channel_host_factory.cc

Index: content/browser/gpu/browser_gpu_channel_host_factory.cc
diff --git a/content/browser/gpu/browser_gpu_channel_host_factory.cc b/content/browser/gpu/browser_gpu_channel_host_factory.cc
index 205542cdc81e918839841fbbeb55d99e16c6cadd..db9abc0ab776677ff862c7dbb8e1c2ef13932469 100644
--- a/content/browser/gpu/browser_gpu_channel_host_factory.cc
+++ b/content/browser/gpu/browser_gpu_channel_host_factory.cc
@@ -254,12 +254,13 @@ bool BrowserGpuChannelHostFactory::IsGpuMemoryBufferFactoryUsageEnabled(
 }
 
 // static
-uint32 BrowserGpuChannelHostFactory::GetImageTextureTarget() {
-  if (!IsGpuMemoryBufferFactoryUsageEnabled(gfx::GpuMemoryBuffer::MAP))
+uint32 BrowserGpuChannelHostFactory::GetImageTextureTarget(
+    gfx::GpuMemoryBuffer::Usage usage) {
+  if (!IsGpuMemoryBufferFactoryUsageEnabled(usage))
     return GL_TEXTURE_2D;
 
   std::vector<gfx::GpuMemoryBufferType> supported_types;
-  GpuMemoryBufferFactory::GetSupportedTypes(&supported_types);
+  GpuMemoryBufferFactory::GetSupportedTypes(usage, &supported_types);

[reveman, 2015/05/19 16:12:12]

Instead of changing GetSupportedTypes (which might be removed soon) I think we
should use IsGpuMemoryBufferConfigurationSupported here to determine what type
is actually going to be used.

Requires adding gfx::GpuMemoryBuffer::Format as the first param to this function
but I think that's what we want. It will return the target to use for a specific
combination of format and usage.

[danakj, 2015/05/19 20:11:52]

I don't understand this request :(

IsGpuMemoryBufferConfigurationSupported(format, usage) returns true if a
format,usage pair is valid. It doesn't take a type as a parameter. Is that what
you are asking for?

The IsGpuMemoryBufferConfigurationSupported() method has no comments explaining
what it is doing so I'm not sure TBH. But for SHARED_MEMORY type it always
returns false. So then how would GetImageTextureTarget decided we're going to
use SHARED_MEMORY ever?

[danakj, 2015/05/19 22:19:43]

OK thanks for the discussion about this! I've passed format to this method
(hardcoded at the callsites with TODOs) and am using a static
IsGMBConfigSupported method to decide to use native or shared memory buffers.

   DCHECK(!supported_types.empty());
 
   // The GPU service will always use the preferred type.
@@ -473,7 +474,7 @@ bool BrowserGpuChannelHostFactory::IsGpuMemoryBufferConfigurationSupported(
 
   // Preferred type is always used by factory.
   std::vector<gfx::GpuMemoryBufferType> supported_types;
-  GpuMemoryBufferFactory::GetSupportedTypes(&supported_types);
+  GpuMemoryBufferFactory::GetSupportedTypes(usage, &supported_types);
   DCHECK(!supported_types.empty());
   switch (supported_types[0]) {
     case gfx::SHARED_MEMORY_BUFFER: