Change ACCELERATED_COMPOSITING blacklist to GPU_COMPOSITING.

content/public/common/content_switches.cc

 // Copyright (c) 2012 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 "content/public/common/content_switches.h"
 
 #include "base/command_line.h"
 
 namespace switches {
 
@@ skipping 20 matching lines @@
 // Allows debugging of sandboxed processes (see zygote_main_linux.cc).
 const char kAllowSandboxDebugging[]         = "allow-sandbox-debugging";
 
 // The same as kAuditHandles except all handles are enumerated.
 const char kAuditAllHandles[]               = "enable-handle-auditing-all";
 
 // Enumerates and prints a child process' most dangerous handles when it
 // is terminated.
 const char kAuditHandles[]                  = "enable-handle-auditing";
 
-// Blacklist the GPU for accelerated compositing.
-const char kBlacklistAcceleratedCompositing[] =
-    "blacklist-accelerated-compositing";
+// Blacklist the GPU for GPU compositing, to force software compositing.
+const char kBlacklistGpuCompositing[] =
+    "blacklist-gpu-compositing";

[piman, 2014/04/16 17:56:13]

What's the use of that over --disable-gpu?

[danakj, 2014/04/16 18:07:43]

I don't know I was going to ask about this. It seemed like this was meant for
testing as if the card was blacklisted somehow. At first I removed it but I'm
not sure if people use it:

1. --disable-gpu causes GpuDataManagerImplPrivate::DisableHardwareAcceleration()
to happen in the constructor.
2. --disable-gpu then sets card_blacklisted_ = true
3. --disable-gpu then puts GPU_COMPOSITING into the blacklisted_features_

Later, GpuDataManagerImplPrivate::Initialize happens which goes to
InitializeImpl:
1. InitializeImpl calls UpdateGpuInfo which calls UpdateGpuInfoHelper
2. UpdateGpuInfoHelper gets a new |features| set from
gpu_blacklist_->MakeDecision
3. This |features| is given to UpdateBlacklistedFeatures 
4. The |features| replaces blacklisted_features_

At this point --disable-gpu has done nothing except mark card_blacklisted =
true.

5. If card_blacklisted_ or kBlacklistGpuCompositing, we add GPU_COMPOSITING back
to blacklisted_features.

So:
- Why does --disable-gpu bother doing anything except set card_blacklisted_ ?
- I don't think this flag is very useful, but then the same argument for
kBlacklistWebGL. Should I remove them both as another CL together?

 
 // Blacklist the GPU for WebGL.
 const char kBlacklistWebGL[]                = "blacklist-webgl";
 
 // Choose which logging channels in blink platform to activate.  See
 // Logging.cpp in blink's Source/platform for a list of available channels.
 const char kBlinkPlatformLogChannels[]      = "blink-platform-log-channels";
 
 // Block cross-site documents (i.e., HTML/XML/JSON) from being loaded in
 // subresources when a document is not supposed to read them.  This will later
@@ skipping 976 matching lines @@
 
 // Disables support for Core Animation plugins. This is triggered when
 // accelerated compositing is disabled. See http://crbug.com/122430 .
 const char kDisableCoreAnimationPlugins[] =
     "disable-core-animation-plugins";
 #endif
 
 // Don't dump stuff here, follow the same order as the header.
 
 }  // namespace switches