Implement fallback from WMPI to WMPA.

content/browser/gpu/gpu_data_manager_impl_private.cc

 // Copyright (c) 2013 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/browser/gpu/gpu_data_manager_impl_private.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
@@ skipping 915 matching lines @@
   const std::string group_name = base::FieldTrialList::FindFullName(
       "DisableAcceleratedVideoDecode");
   if (command_line->HasSwitch(switches::kDisableAcceleratedVideoDecode)) {
     // It was already disabled on the command line.
     return false;
   }
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_ACCELERATED_VIDEO_DECODE))
     return true;
   if (group_name == "Disabled")
     return true;
+
+  // Accelerated decode is never available with --disable-gpu. It is also
+  // currently non-functional with --single-process and --in-process-gpu, but
+  // these should be fixable. We set the --disable-accelerated-video-decode flag
+  // in these cases so that the renderer can be aware. (Which is important on
+  // Android where there is no fallback once WMPI is selected.)
+  //
+  // TODO(sandersd): Enable support for accelerated decode with
+  // --in-process-gpu, at least on Android (necessary to support WebView).

[DaleCurtis, 2016/01/06 22:54:40]

Does WebView only use --in-process-gpu and not --single-process?

[sandersd (OOO until July 31), 2016/01/07 00:08:38]

WebView may use either, depending on other settings and the device. They are
slightly different though, in --single-process mode compositing is synchronous
(which I understand to be an exposed API feature of WebView).

+  // http://crbug.com/574935.
+  if (command_line->HasSwitch(switches::kDisableGpu) ||
+      command_line->HasSwitch(switches::kSingleProcess) ||
+      command_line->HasSwitch(switches::kInProcessGPU)) {
+    return true;
+  }
+
   return false;
 }
 
 void GpuDataManagerImplPrivate::GetDisabledExtensions(
     std::string* disabled_extensions) const {
   DCHECK(disabled_extensions);
   *disabled_extensions = disabled_extensions_;
 }
 
 void GpuDataManagerImplPrivate::BlockDomainFrom3DAPIs(
@@ skipping 280 matching lines @@
   gpu_info_.context_info_state = gpu::kCollectInfoFatalFailure;
 #if defined(OS_WIN)
   gpu_info_.dx_diagnostics_info_state = gpu::kCollectInfoFatalFailure;
 #endif
   complete_gpu_info_already_requested_ = true;
   // Some observers might be waiting.
   NotifyGpuInfoUpdate();
 }
 
 }  // namespace content