Don't share renderers between unrelated tabs on Android.

content/browser/android/content_startup_flags.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/browser/android/content_startup_flags.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "cc/base/switches.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/common/content_constants.h"
 #include "content/public/common/content_switches.h"
 #include "gpu/command_buffer/service/gpu_switches.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/native_theme/native_theme_switches.h"
 
 namespace content {
 
-void SetContentCommandLineFlags(int max_render_process_count,
+void SetContentCommandLineFlags(bool in_process,
                                 const std::string& plugin_descriptor) {
   // May be called multiple times, to cover all possible program entry points.
   static bool already_initialized = false;
   if (already_initialized)
     return;
   already_initialized = true;
 
   CommandLine* parsed_command_line = CommandLine::ForCurrentProcess();
 
   int command_line_renderer_limit = -1;
   if (parsed_command_line->HasSwitch(switches::kRendererProcessLimit)) {
     std::string limit = parsed_command_line->GetSwitchValueASCII(
         switches::kRendererProcessLimit);
     int value;
     if (base::StringToInt(limit, &value)) {
-      command_line_renderer_limit = value;
-      if (value <= 0)
-        max_render_process_count = 0;
+      command_line_renderer_limit = std::max(0, value);
     }
   }
 
   if (command_line_renderer_limit > 0) {
     int limit = std::min(command_line_renderer_limit,
                          static_cast<int>(kMaxRendererProcessCount));
     RenderProcessHost::SetMaxRendererProcessCount(limit);
-  } else if (max_render_process_count <= 0) {
+  }
+
+  if (in_process) {

[klobag.chromium, 2014/06/27 16:25:42]

hmm what happen is command_line_renderer_limit > 0 and in_process is true?

[ppi, 2014/06/27 16:40:32]

Nothing in particular. It already can happen - the single process flag doesn't
depend on the process limit having any particular value afaiu. 

[ppi, 2014/07/16 13:26:54]

Oh, I see there is a change in behavior. If both command_line_renderer_limit > 0
is set *and* the embedder requests single process mode, then:

- before: single process mode is ignored, renderer process limit override is set
- after: single process mode is honored (renderer process limit is also set but
it doesn't affect single process)

It feels reasonable to me, wdyt?

Also, in patch set 4 I restored the option to set singleProcess by passing
command_line_renderer_limit = 0, matching previous behavior.

     // Need to ensure the command line flag is consistent as a lot of chrome
     // internal code checks this directly, but it wouldn't normally get set when
     // we are implementing an embedded WebView.
     parsed_command_line->AppendSwitch(switches::kSingleProcess);
-  } else {
-    int default_maximum = RenderProcessHost::GetMaxRendererProcessCount();
-    DCHECK(default_maximum <= static_cast<int>(kMaxRendererProcessCount));
-    if (max_render_process_count < default_maximum)
-      RenderProcessHost::SetMaxRendererProcessCount(max_render_process_count);
   }
 
   parsed_command_line->AppendSwitch(switches::kEnableThreadedCompositing);
   parsed_command_line->AppendSwitch(
       switches::kEnableCompositingForFixedPosition);
   parsed_command_line->AppendSwitch(switches::kEnableAcceleratedOverflowScroll);
   parsed_command_line->AppendSwitch(switches::kEnableBeginFrameScheduling);
 
   parsed_command_line->AppendSwitch(switches::kEnableGestureTapHighlight);
   parsed_command_line->AppendSwitch(switches::kEnablePinch);
@@ skipping 25 matching lines @@
   }
 
   // Disable profiler timing by default.
   if (!parsed_command_line->HasSwitch(switches::kProfilerTiming)) {
     parsed_command_line->AppendSwitchASCII(
         switches::kProfilerTiming, switches::kProfilerTimingDisabledValue);
   }
 }
 
 }  // namespace content